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Sisal cellulose whiskers reinforced polyvinyl acetate nanocomposites
Microsoft Academic Search
Sisal nanowhiskers were used as novel reinforcement to obtain nanocomposites with polyvinyl acetate (PVAc) as matrix phase. They are seen as attractive materials due to the widespread availability and low cost of the sisal source material. Statistical analysis of the sisal whisker length and diameter resulted in average values of 250Ānm and 4Ānm, respectively, resulting in an average aspect ratio
Nancy Lis Garcia de Rodriguez; Wim Thielemans; Alain Dufresne
Viscometric study of poly(vinyl chloride)\\/poly(vinyl acetate) blends in various solvents
The intermolecular interactions between poly(vinyl chloride) (PVC) and poly(vinyl acetate) (PVAc) in tetrahydrofuran (THF), methyl ethyl ketone (MEK) and N,N?-dimethylformamide (DMF) were thoroughly investigated by the viscosity measurement. It has been found that the solvent selected has a great influence upon the polymer¢polymer interactions in solution. If using PVAc and THF, or PVAc and DMF to form polymer solvent, the
Yuchuan Zhang; Jiasheng Qian; Zhuo Ke; Xiangcheng Zhu; Hong Bi; Kangming Nie
Poly(vinyl acetal)s containing electron-donor groups: Synthesis in homogeneous phase and their thermal properties
The condensation reaction of 1-Naphthaldehyde (NA), 9-Anthraldehyde (ANTA), 9-Ethyl-3-carbazolecarboxaldehyde (ECZA) with poly(vinyl alcohol) (PVA) to give poly(vinyl acetal)s (PVAcs) was studied in detail using N-methyl-2-pyrrolidone (NMP) as solvent for PVA and PVAcs. PVAcs having various degrees of acetalization were obtained. The acetalization reaction under a variety of conditions gave at best a poly[2-(1-naphthyl)-1,3-dioxan-4,6-diylmethylene] (PNA) with 78% acetalization, poly[2-(9-anthryl)-1,3-dioxan-4,6-diylmethylene] (PANTA) with
M. D. Fernßndez; M. J. Fernßndez; P. Hoces
Preparation of poly(vinyl acetate)\\/clay and poly(vinyl acetate)\\/poly(vinyl alcohol)\\/clay microspheres
Poly(vinyl acetate) (PVAc)\\/poly(vinyl alcohol)(PVA)\\/montmorillonite (MMT) clay nanocomposite microspheres with a core\\/shell\\u000a structure have been developed via a suspension polymerization approach. In order to prepare the PVAc\\/MMT and PVAc\\/PVA\\/MMT\\u000a nanocomposite microspheres, which are promising precursor of PVA\\/MMT nanocomposite microspheres, suspension polymerization\\u000a of vinyl acetate with organophilic MMT and heterogeneous saponification were conducted. A quaternary ammonium salt, cetyltrimethylammonium\\u000a bromide, was mixed with
Hye Min Jung; Eun Mi Lee; Byung Chul Ji; Sung Ok Sohn; Han Do Ghim; Hyunju Cho; Young A Han; Jin Hyun Choi; Jae Deuk Yun; Jeong Hyun Yeum
Preparation of poly(vinyl acetate) having a DMSO-like structure, and its use in accelerating penetration through paper
Poly(vinyl acetate) (PVAc) has been transformed into a polymer having the structure of PVAcSOMe via hydrolysis, 3-methylthiopropionylation and oxidation. The obtained PVAcSOMe copolymers have been shown to have the property of accelerating the penetration of triphenylphosphite through parchment paper.
T. Yamamoto; K. Mori; T. Fujiwara
EPA Science Inventory
Hybrid blends of poly(amidoamine) PAMAM dendrimers with two linear high polymers, poly(vinyl chloride), PVC, and poly(vinyl acetate), PVAc, are reported. The interaction between the blend components was studied using dynamic mechanical analysis, xenon nuclear magnetic resonacne ...
Poly(vinyl acetate)\\/poly(vinyl alcohol)\\/montmorillonite nanocomposite microspheres prepared by suspension polymerization and saponification
Poly(vinyl acetate) (PVAc)¢poly(vinyl alcohol)¢montmorillonite (MMT) nanocomposite microspheres were prepared through suspension\\u000a polymerization followed by the heterogeneous saponification. The effects of MMT on the polymerization rate and the saponification\\u000a rate of PVAc were studied. It was found that the rate of polymerization decreased when MMT content was increased. However,\\u000a the saponification rate of PVAc significantly increased in the presence of nanoclay
Hye Min Jung; Eun Mi Lee; Byung Chul Ji; Yulin Deng; Jae Deuk Yun; Jeong Hyun Yeum
Improved adhesive strength and toughness of polyvinyl acetate glue on addition of small quantities of graphene.
We have prepared composites of polyvinyl acetate (PVAc) reinforced with solution exfoliated graphene. We observe a 50% increase in stiffness and a 100% increase in tensile strength on addition of 0.1 vol % graphene compared to the pristine polymer. As PVAc is commonly used commercially as a glue, we have tested such composites as adhesives. The adhesive strength and toughness of the composites were up to 4 and 7 times higher, respectively, than the pristine polymer. PMID:23362791
Khan, Umar; May, Peter; Porwal, Harshit; Nawaz, Khalid; Coleman, Jonathan N
Cosolvent gel-like materials from partially hydrolyzed poly(vinyl acetate)s and borax.
A gel-like, high-viscosity polymeric dispersion (HVPD) based on cross-linked borate, partially hydrolyzed poly(vinyl acetate) (xPVAc, where x is the percent hydrolysis) is described. Unlike hydro-HVPDs prepared from poly(vinyl alcohol) (PVA) and borate, the liquid portion of these materials can be composed of up to 75% of an organic cosolvent because of the influence of residual acetate groups on the polymer backbone. The effects of the degree of hydrolysis, molecular weight, polymer and cross-linker concentrations, and type and amount of organic cosolvent on the rheological and structural properties of the materials are investigated. The stability of the systems is explored through rheological and melting-range studies. (11)B NMR and small-angle neutron scattering (SANS) are used to probe the structure of the dispersions. The addition of an organic liquid to the xPVAc-borate HVPDs results in a drastic increase in the number of cross-linked borate species as well as the agglomeration of the polymer into bundles. These effects result in an increase in the relaxation time and thermal stability of the networks. The ability to make xPVAc-borate HVPDs with very large amounts of and rather different organic liquids, with very different rheological properties that can be controlled easily, opens new possibilities for applications of PVAc-based dispersions. PMID:21848256
Angelova, Lora V; Terech, Pierre; Natali, Irene; Dei, Luigi; Carretti, Emiliano; Weiss, Richard G
Potential Barriers and Internal Rotation in Polyvinyl Acetate and Poly-o-Fluorostyrene,
National Technical Information Service (NTIS)
The present work is devoted to presenting the results of a calculation of potential barriers of internal rotation in the side pendant of some polymers, namely polyvinyl acetate (PVAc) and poly-o-fluorostyrene (POFS), connected namely with the steric repul...
Y. Y. Gotlib A. A. Darinskiy
Compatibility studies on solution of polystyrene and polyvinyl acetate blend by density and viscometric methods
Density and viscometric studies were conducted on solutions of blends of polystyrene (PS) and polyvinyl acetate (PVAc) at 30 ░C in toluene, methyl ethyl ketone (MEK) and tetrahydrofuran (THF) at 2% total solid content. Experimental densities of the blends were found to be lower than the calculated values assuming additivity of volumes of polymers and solvent. The plots of relative
P. A. A. P. Mamza; F. M. Folaranmi
Combined XPS and contact angle studies of ethylene vinyl acetate and polyvinyl acetate blends
NASA Astrophysics Data System (ADS)
In this study, we prepared thin films by blending ethylene vinyl acetate copolymers (EVA) containing 12-33 (wt.%) vinyl acetate (VA) with polyvinyl acetate (PVAc) and high density polyethylene homopolymers. Large area micropatterns having controlled protrusion sizes were obtained by phase-separation especially for the PVAc/EVA-33 blends using dip coating. These surfaces were characterized by XPS and contact angle measurements. A reasonably linear relation was found between the VA content on the surface (wt.%) obtained from XPS analysis and the VA content in bulk especially for PVAc/EVA-33 blend surfaces. PE segments were more enriched on the surface than that of the bulk for pure EVA copolymer surfaces similar to previous reports and VA enrichment was found on the EVA/HDPE blend surfaces due to high molecular weight of HDPE. Water ? decreased with the increase in the VA content on the blend surface due to the polarity of VA. A good agreement was obtained between ?s- and atomic oxygen surface concentration with the increase of VA content. The applicability of Cassie-Baxter equation was tested and found that it gave consistent results with the experimental water contact angles for the case where VA content was lower than 55 wt.% in the bulk composition.
Ucar, I. O.; Doganci, M. D.; Cansoy, C. E.; Erbil, H. Y.; Avramova, I.; Suzer, S.
Amphiphilic conjunct of methyl cellulose and well-defined polyvinyl acetate.
Tailor-made conjunct of methyl cellulose (MC) and polyvinyl acetate (PVAc) was synthesized through the combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and thiol-ene click reaction. MC was firstly transferred into unsaturated MC (UMC), and then covalently connected with well-defined PVAc obtained by RAFT polymerization of vinyl acetate. The structure of the conjunct polymer (MCV) was confirmed with Fourier transform infrared spectra (FTIR) and proton nuclear magnetic resonance ((1)H NMR). Well-defined MCV was amphiphilic and able to self-assemble into size controllable micelles, which was verified with transmission electron microscopy (TEM) and size distribution analysis. It was found that the mean diameters of the micelles in aqueous solution were 105.6, 96.0 and 75.9 nm when the number average molecular weights of PVAc segments of MCV were 49,300, 32,500 and 18,200, respectively. PMID:23107808
Xiao, Congming; Xia, Cunping
The influence of UV-irradiation on poly(vinyl chloride) modified by poly(vinyl acetate)
The influence of small amount of poly(vinyl acetate) (PVAC) on poly(vinyl chloride) (PVC) photooxidative degradation was investigated by FTIR, UV-Vis and solid state 13C-NMR spectroscopy. The gel amount formed in exposed samples was estimated gravimetrically. Moreover, surface free energy of PVC+PVAC films was calculated on the base of contact angle measurements. It was found that PVAC decelerates PVC photodegradation, photocrosslinking and photooxidation leading to carbonyl groups formation. This effect is caused by an efficient quenching of macroradicals by low radicals formed in primary photochemical reactions in both polymeric phases. UV-irradiation leads to significant changes of surface properties in all samples studied. In most cases surface free energy decreases with irradiation time but it is caused by an efficient drop of its dispersive component whereas polar component markedly increases due to the formation of functional groups. The mechanism of observed photochemical processes including interactions between both components has been discussed. The influence of sample morphology on the course of photochemical reaction and protection effect induced by carbonyl groups from PVAC was also suggested.
Kaczmarek, Halina; Drag, Renata; ?wi?tek, Ma?gorzata; O?dak, Dagmara
Synthesis of poly(vinyl acetate-methyl methacrylate) copolymer microspheres using suspension polymerization.
Poly(vinyl acetate-methyl methacrylate) (VAc-MMA) copolymer microspheres were prepared using suspension polymerization at low temperature initiated with 2,2'-azobis(2,4-dimethyl valeronitrile) (ADMVN). The poly(VAc-MMA) copolymer microspheres can be used over a large area where homopolymers, polyvinyl acetate (PVAc) and methyl methacrylate (PMMA) microspheres are capable of being put to use. The prepared microspheres were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Obtained copolymer microspheres which have 200 ?m average diameter and higher thermal stability than those of homopolymer. PMID:22137854
Islam, Md Shahidul; Yeum, Jeong Hyun; Das, Ajoy Kumar
Synthesis of Novel Well-Defined Poly(vinyl acetate)-b-poly(acrylonitrile) and Derivatized Water-Soluble Poly(vinyl alcohol)-b-poly(acrylic acid) Block Copolymers by Cobalt-Mediated Radical Polymerization
Poly(vinyl acetate)┐Co(acac)2 macroinitiators, prepared by cobalt-mediated radical polymerization of vinyl acetate (VAc), were used to synthesize well-defined poly(vinyl acetate)-b-poly(acrylonitrile) (PVAc-b-PAN) block copolymers. Different solvents and temperatures were tested for the polymerization of the acrylonitrile segment by cobalt-mediated radical polymerization (CMRP), and copolymers with low polydispersity were obtained provided that dimethylformamide was used as solvent at 0 ░C. The mechanism of
Antoine Debuigne; Jķr¶me Warnant; Robert Jķr¶me; Ilja Voets; Arie de Keizer; Martien A. Cohen Stuart; Christophe Detrembleur
Structure And Dynamics Of Semi-crystalline Polyethylene Oxide / Polyvinyl Acetate Blends
The structure and dynamics of semi-crystalline, melt-miscible polyethylene oxide / polyvinyl acetate (PEO/PVAc) blends were investigated using small-angle X-ray scattering and dielectric relaxation spectroscopy. PEO/PVAc blends with selected compositions were crystallized at various temperatures. Small-angle X-ray scattering was used to quantitatively determine the semi-crystalline microstructure, including the location(s) of the non-crystallizable PVAc in the structure. Segmental and local dynamics were studied using broadband dielectric relaxation spectroscopy. We attempt to clarify the origin of an additional relaxation, located at intermediate frequencies between the segmental and local processes, which has been proposed to be related to initial stages of crystallization even in blends lacking macroscopic crystallinity.
Runt, James; Fragiadakis, Daniel
Characterization of Sidegroup Packing in Methacrylates and Poly(Vinyl Acetate) by Solid-State NMR
The local packing of sidegroups in poly(vinyl acetate), PVAc, poly(ethyl methacrylate), PEMA, and poly(methyl methacrylate), PMMA, was studied by two-dimensional solid-state NMR experiments applied to ^13COO-labeled polymers. Relative sidegroup orientations were determined by double-quantum chemical-shift-anisotropy correlation, while intergroup distances were measured from dipolar splittings. The spectra of PEMA show that while sidegroups are not exactly parallel to each other, the
Douglas J. Harris; Tito J. Bonagamba; Klaus Schmidt-Rohr
Degradation kinetics of poly(vinyl acetate) in the presence of aluminum chloride
The thermal degradation of poly(vinyl acetate) (PVAc) was carried out in the presence of various concentrations of aluminum chloride (AlCl3) at different temperatures. The time evolution of molecular weight distributions (MWDs) was determined by gel permeation chromatography. A continuous distribution kinetic model was used to evaluate the degradation rate coefficient assuming the reaction is first order in polymer concentration and
Sujay Chattopadhyay; Giridhar Madras
Photochemical degradation study of polyvinyl acetate paints used in artworks by Py-GC/MS.
Photochemical degradation of commercial polyvinyl acetate (PVAc) homopolymer and PVAc paints mixed with burnt umber, cobalt blue, cadmium red dark, nickel azo yellow and titanium white commonly used for artworks were studied by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR). Py-GC/MS with single-shot technique was used for the characterization of the thermal degradation of PVAc at different temperatures, while the double-shot technique of Py-GC/MS was used to reveal the differences in the specimens before and after UV ageing, including the changes of detectable amounts of deacetylation product - acetic acid and plasticizers such as diethyl phthalate (DEP). Furthermore, the relative concentration of the pyrolysis products of the paint samples could be measured and compared in the second step of the double-shot Py-GC/MS, which are highly dependent on the presence of pigments and the ageing status of PVAc paints. PMID:23024446
Wei, Shuya; Pintus, Valentina; Schreiner, Manfred
Spectroscopic and thermal studies of PS\\/PVAc blends
Polystyrene and polyvinyl acetate (PS\\/PVAc) films were blended with different contents using casting method. The effect of PS content on PVAc blends was investigated by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Ultra violet and visible studies (UV\\/VIS), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Significant changes in FT-IR, XRD and DSC analysis are observed which reveals an interactions
I. S. Elashmawi; N. A. Hakeem; E. M. Abdelrazek
Poly(ethylene oxide) Dynamics in Blends with Poly(vinyl acetate)
^2H NMR relaxation measurements were performed to study the segmental dynamics of perdeuteropoly(ethylene oxide) (d4PEO) in miscible blends with poly(vinyl acetate) (PVAc). For two compositions (2% and 50% d4PEO), spin-lattice relaxation times were measured in a temperature range well above Tg. Over the temperature range studied, the segmental dynamics of the PEO component in 2% PEO/PVAc blend is almost the same as that in 3% PEO/PMMA blend reported by Lutz et al. (Macromolecules 2003, 36, 1724-1730), even though the Tg of PVAc is 100K lower than that of PMMA. In the 2% d4PEO blend, the segmental dynamics of PEO is 9 orders of magnitude faster than PVAc segmental dynamics at the blend Tg. For the two compositions studied, segmental dynamics of the PEO component can be well described by L-M model with a self-concentration of 0.3. By comparing the segmental correlation times of the PEO component with viscoelastic shift factors reported by Urakawa et al. (J. Non-Crystalline Solids 352, 2006 5042-5049), it is found that the temperature dependence of the segmental dynamics of the PEO component is weaker than the temperature dependence of the PEO terminal dynamics.
Zhao, Junshu; Ediger, Mark
Nanogels based on poly(vinyl acetate) for the preparation of patterned porous films.
The use of poly(vinyl acetate) (PVAc) nanogels for the fabrication of patterned porous surfaces is described. These nanogels were synthesized by controlled radical cross-linking copolymerization (CRCC) involving a xanthate-mediated reversible addition-fragmentation chain transfer (RAFT) mechanism. This synthesis methodology allowed for the preparation of nanogels based on PVAc with a controlled constitutive chain length and average numbers of chains and cross-links. Solutions of these branched polymers were prepared in THF with a fixed amount of water and spin coated onto a surface of graphite. The surface porosity of corresponding films was observed by atomic force microscopy (AFM). Compared with linear PVAc homologues with a degree of polymerization (DP) sufficiently high to favor the formation of porous structures (DP = 50), a sharper and better defined porosity was observed with nanogels, the constitutive chains of which had the same DP. For nanogels differing only in their cross-link density, the pores were smaller and better defined in the case of the higher cross-link density, suggesting an enhanced stabilization of the water droplets during film formation. To explain these observations, it is postulated that PVAc nanogels can behave as compact particles providing steric stabilization of water droplets, which is referred to as a Pickering effect. The coalescence of water droplets would be better prevented as the cross-link density of the nanogels increases, resulting in a smaller size pore. PMID:21417321
Poly, Julien; Ibarboure, Emmanuel; Le Meins, Jean-Franńois; Rodriguez-Hernandez, Juan; Taton, Daniel; Papon, Eric
Method development for compositional analysis of low molecular weight poly(vinyl acetate) by matrix-assisted/laser desorption-mass spectrometry and its application to analysis of chewing gum.
The influence of the sample preparation parameters (the choice of the solvent and of the matrix:analyte ratio) was investigated and optimal conditions were established for MALDI mass spectrometry analysis of the pristine low molecular weight polyvinyl acetate (PVAc). It was demonstrated that comparison of polymer's and solvent's Hansen solubility parameters could be used as a guide when choosing the solvent for MALDI sample preparation. The highest intensity PVAc signals were obtained when ethyl acetate was used as a solvent along with the lowest matrix-analyte ratio (2,5-dihydroxybenzoic acid was used as a matrix in all experiments). The structure of the PVAc was established with high accuracy using the matrix-assisted laser desorption/ionization-Fourier transform mass spectrometry (MALDI-FTMS) analysis. It was demonstrated that PVAc undergoes unimolecular decomposition by losing acetic acid molecules from its backbone under the conditions of FTMS measurements. Number and weight average molecular weights as well as polydispersity indices were determined with both MALDI-TOF and MALDI-FTMS methods. The sample preparation protocol developed was applied to the analysis of a chewing gum and the molecular weight and structure of the polyvinyl acetate present in the sample were established. Thus, it was shown that optimized MALDI mass spectrometry could be used successfully for characterization of polyvinyl acetate in commercially available chewing gum. PMID:24745742
Tisdale, Evgenia; Wilkins, Charles
Temperature divergence of the dynamics of a poly(vinyl acetate) glass: dielectric vs. mechanical behaviors.
The dynamics of glass forming liquids as the glass transition temperature (T(g)) is traversed has become of special interest because of the continuing question as to whether or not the dynamics diverge towards an ideal glass transition/Kauzmann temperature or if the apparent Vogel-Fulcher-Tammann (VFT) divergence is lost as one goes below the conventional T(g) but remains in equilibrium. Here we examine the response of a poly(vinyl acetate) PVAc polymer glass-former using both dielectric and mechanical methods in the vicinity of T(g). Isothermal measurements were performed to study the aging behavior of the PVAc and to assure that the equilibrium state was achieved for temperatures as much as 16 K below the calorimetric T(g). Surprisingly, we found that the mechanical response took much longer to age into its equilibrium than did the dielectric response. Also, the temperature dependence of the time-temperature shift factors obtained from the two methods is different and the dielectric response shows a turnover to an apparent Arrhenius behavior rather than a continuation of the VFT extrapolated divergence at the lowest temperatures tested. PMID:22519344
Zhao, Jing; McKenna, Gregory B
DMA Analysis of PVAc Latex Reinforced with Cellulose Nanofibrils
Suspensions of commercial refined and bleached beech wood pulp (RBP) were further processed through mechanical disintegration (MD-RBP), chemical modification (CM-RBP), or through chemical modification followed by mechanical disintegration (CM-MD-RBP). Nanocomposites were prepared by compounding a poly(vinyl acetate) (PVAc) latex adhesive with increasing contents of the untreated RBP or the processed nanofibrils, and the resulting nanocomposites were analyzed by dynamic mechanical
Francisco L¾pez-Suevos; Christian Eyholzer; Nico Bordeanu
Solvatochromism in the visible absorption band of 4-dimethylamino-4?-nitroazobenzene in polystyrene and poly(vinyl acetate), and in model liquid solvents: Effects of temperature, medium polarity, and rigidity
Temperature-induced solvatochromism in the visible absorption band of 4-dimethylamino-4?-nitroazobenzene (diMANA) dissolved in polystyrene (PS) and poly(vinyl acetate) (PVAc), and in toluene and ethyl acetate used as model liquid solvents was investigated. In all solutions under study the absorption band maximum shifts to blue, and the magnitude of the transition moment slightly diminishes as temperature rises. In polymer solid solution the
B. Nadolski; P. Uzna?Ski; M. Kryszewski
Polyvinyl acetate-based film coatings.
Polyvinyl acetate-based colloidal aqueous polymer dispersion Kollicoat(«) SR 30 D results in coatings characterized by moderate swelling behaviour, lipophilicity, pH-independent permeability for actives and high flexibility to withstand mechanical stress and is therefore used for controlled release coating. The colloidal aqueous polymer dispersion of Kollicoat(«) SR 30 D can be easily processed due to an optimal low minimum film forming temperature (MFT) of 18 ░C without plasticizer addition and a thermal after-treatment (curing) of coated pellets. The drug release from Kollicoat(«) SR 30 D coated pellets was almost pH independent. Drug release could be easily adjusted by coating level or addition of soluble pore forming polymers. Physically stable Kollicoat(«) SR 30 D dispersions were obtained with the water-soluble polymers Kollidon(«) 30 and Kollicoat(«) IR up to 50% w/w. The addition of only 10% w/w triethyl citrate as plasticizer improved the flexibility of the films significantly and allowed compaction of the pellets. The drug release was almost independent of the compression force and the pellet content of the tablets. The inclusion of various tableting excipients slightly affected the drug release, primarily because of a different disintegration rate of the tablets. A combination of Kollicoat(«) SR 30 D and Kollicoat(«) IR with higher coating levels>10 mg/cm(2) is a relatively new alternative to OROS system which does not require drilling. PMID:24076229
Kolter, K; Dashevsky, A; Irfan, Muhamad; Bodmeier, R
Miscibility of cellulose acetate with vinyl polymers
Binary blend films of cellulose acetate (CA) with flexible syntheticpolymers including poly(vinyl acetate) (PVAc), poly(N-vinyl pyrrolidone) (PVP),and poly(N-vinyl pyrrolidone-co-vinyl acetate) [P(VP-co-VAc)] were preparedfrommixed polymer solutions by solvent evaporation. Thermal analysis by DSC showedthat CA of any degree of substitution (DS) was not miscible with PVAc, but CAwith DS less than 2.8 was miscible with PVP to form homogeneous blends. Thestate
Yoshiharu Miyashita; Tetsuya Suzuki; Yoshiyuki Nishio
Photo-fries rearrangements of 1-naphthyl esters in the glassy and melted states of poly(vinyl acetate). Comparisons with reactions in less polar polymers and low-viscosity solvents.
The photo-Fries and associated photoreactions of four 1-naphthyl acylates have been examined in two types of poly(vinyl acetate) (PVAc) films above and below their glass transition temperatures, Tg. Because of the 'templating' effect of the esters on their reaction cavities, especially below Tg, the distributions of photo-Fries products, as mandated by the intermediate acyl/1-naphthyloxyl singlet radical pairs, are determined largely by the initial conformations of the guest molecules. Even above Tg, at 50 degrees C, where segmental chain motions of PVAc are relatively rapid, the influence of the cages in directing product formation is apparent. The radical-pair recombination rates for formation of the keto precursor of 2-(2-phenylpropanoyl)-1-naphthol upon irradiation of 1-naphthyl 2-phenylpropanoate in PVAc are reduced drastically as the temperature is lowered from above to below Tg. Comparison of results in PVAc with those in low-viscosity solvents (ethyl acetate and hexane) and low-polarity polymer films (polyethylene and polypropylene) indicate that interactions between the radicals produced from irradiation of 1 and the acetate pendant groups of PVAc, as well as the nature of its chain motions above and below Tg, influence enormously the course of the photo-Fries rearrangements. PMID:12659149
Gu, Weiqiang; Bi, Shuguang; Weiss, Richard G
Structural and mechanical properties of "peelable" organoaqueous dispersions with partially hydrolyzed poly(vinyl acetate)-borate networks: applications to cleaning painted surfaces.
The preparation and structural characterization of a family of viscoelastic dispersions of borate cross-linked, 80% hydrolyzed poly(vinyl acetate) (80PVAc) in aqueous-organic liquids are presented. Correlations between mechanical properties (from rheological measurements) and the degree and nature of cross-linking (from (11)B NMR spectroscopy) are reported, and the results are used to assess their potential as low-impact cleaning agents for the surfaces of paintings. Because the dispersions can be prepared at room temperature by simple procedures from readily available materials and can contain up to 50% (w/w) of an organic liquid, they offer important advantages over previously described cleaning agents that are based on fully hydrolyzed PVAc (i.e., poly(vinyl alcohol). The mechanical properties of the various aqueous-organic dispersions, as determined quantitatively by rheological investigations and qualitatively by their ease of removal from a solid surface (i.e., the so-called "peel-off" ability) have been tuned systematically by varying the amount of organic liquid, its structure, and the concentrations of borax and 80PVAc. The (11)B NMR studies demonstrate that the concentration of borate ions actively participating in cross-linking increases significantly with the amount of organic liquid in the mixture. The degree of cross-linking remains constant when the 80PVAc and borax concentrations are varied, as long as their ratios are kept constant. Some of the 80PVAc-borax dispersions have been tested successfully as cleaning agents on the surface of a 16th-17th century oil-on-wood painting by Lodovico Cardi, "Il Cigoli", that was covered by a brown patina and on the surface of a Renaissance wall painting by Vecchietta in Santa Maria della Scala, Siena, Italy, that had a degraded polyacrylate coating from a previous conservation treatment. PMID:21749078
Natali, Irene; Carretti, Emiliano; Angelova, Lora; Baglioni, Piero; Weiss, Richard G; Dei, Luigi
Thermal degradation kinetics of poly(vinyl chloride-co-vinyl acetate)
The kinetics of thermal degradation of three vinyl chloride-co-vinyl acetate (PVC-co-PVAc) copolymers with PVAc content of 14, 14 and 10 wt.% was investigated at various temperatures (220¢250Ā░C) in solution. Reaction samples were analyzed by gel permeation chromatography (GPC) to obtain the molecular weight distribution (MWD). The degradation rate coefficients were determined from the time evolution of the MWDs. The energies
Effect of poly(vinyl acetate) on structures and properties of PbZr0.52Ti0.48O3 thick films
PbZr0.52Ti0.48O3 (PZT) thick films are prepared by a polymer-assisted metallo-organic compound decomposition process. The addition of a polymer, poly(vinyl acetate) (PVAc), in PZT precursor solutions promotes the formation of the perovskite phase. Meanwhile, the crack formation is effectively suppressed. The single-layer thickness of PZT films increases from 0.07 to 0.22 ?m. It is found that PZT recrystallizes after the PVAc-related organic compounds are decomposed. Nanosized pores are observed in the morphological surfaces of PZT thick films. The crack-free PZT thick films with thickness of 1.3 ?m by the repeated deposition exhibit good electrical properties with dielectric constant of 996, dielectric loss around of 3%, remanent polarization of 36.3 ?C/cm2, and coercive field of 78.5 kV/cm, which are potential candidates for microelectromechanical system (MEMS) applications.
Lin, Peng; Ren, Wei; Wu, Xiaoqing; Shi, Peng; Yan, Xin; Yao, Xi
Novel Poly(vinyl alcohol)\\/Clay Nanocomposite Microspheres via Suspension Polymerization and Saponification
Poly(vinyl alcohol) (PVA)\\/montmorillonite (MMT) clay nanocomposite microspheres were synthesized through suspension polymerization followed by the heterogeneous saponification for the first time. The effects of MMT on the saponification rate of poly(vinyl acetate) (PVAc) microspheres were studied. It was found that the saponification rate of PVAc significantly increased in the presence of MMT particles. The molecular weight of extracted PVA from
Jeong Hyun Yeum
Effects of Thermal Curing Conditions on Drug Release from Polyvinyl Acetate¢Polyvinyl Pyrrolidone Matrices
This study aimed to investigate the effects of dry and humid heat curing on the physical and drug release properties of polyvinyl\\u000a acetate¢polyvinyl pyrrolidone matrices. Both conditions resulted in increased tablet hardness; tablets stored under humid\\u000a conditions showed high plasticity and deformed during hardness testing. Release from the matrices was dependent on the filler's\\u000a type and level. Release profiles showed
Hatim S. AlKhatib; Saja Hamed; Mohammad K. Mohammad; Yasser Bustanji; Bashar AlKhalidi; Khaled M. Aiedeh; Samer Najjar
Poly(vinyl acetate), poly((1- O-(vinyloxy) ethyl-2,3,4,6-tetra- O-acetyl-?- d-glucopyranoside) and amorphous poly(lactic acid) are the most CO 2-soluble oxygenated hydrocarbon-based polymers
Poly(vinyl acetate), PVAc, remains the most CO2-soluble non-fluorous polymer identified to date. Small sugar acetates are known to be extraordinarily CO2-philic, but cellulose triacetate, a crystalline high molecule weight polymer is CO2 insoluble. Therefore, an amorphous high molecular weight polymer with pendant sugar acetates was synthesized. This polymer, poly(1-O-(vinyloxy) ethyl-2,3,4,6-tetra-O-acetyl-?-d-glucopyranoside, P(AcGIcVE), was indeed CO2-soluble, however cloud point pressures of P(AcGIcVE)
D. Tapriyal; Y. Wang; R. M. Enick; J. K. Johnson; J. Crosthwaite; M. C. Thies; I. H. Paik; A. D. Hamilton
DMA analysis and wood bonding of PVAc latex reinforced with cellulose nanofibrils
Suspensions of commercial refined beech pulp (RBP) were further processed through mechanical disintegration (MD-RBP), chemical\\u000a modification (CM-RBP) and through chemical modification followed by mechanical disintegration (CM-MD-RBP). Nanocomposites\\u000a were prepared by compounding a poly(vinyl acetate) (PVAc) latex adhesive with increasing contents of the different types of\\u000a nanofibrils, and the resulting nanocomposites were analyzed by dynamic mechanical analysis (DMA). Also, the suitability
Francisco L¾pez-Suevos; Christian Eyholzer; Nico Bordeanu; Klaus Richter
Li-ion conduction in PVAc based polymer blend electrolytes for lithium battery applications
The present work describes the Li-ion conduction in Poly(vinyl acetate) (PVAc) based polymer blend electrolytes have been synthesized by solvent casting technique for lithium battery applications. Characterization by XRD, SEM, AFM, FTIR, TG\\/DTA and photoluminescence was performed for synthesized polymer electrolytes. The thermal behaviour of the samples was ascertained from differential scanning calorimeter (DSC) and TG\\/DTA. The temperature dependence of
M. Ulaganathan; S. Sundar Pethaiah; S. Rajendran
Study of miscibility and interaction in polyvinyl chloride-polyvinyl acetate blend using ultrasonic technique
The propagation of ultrasonic waves and the measurement of their velocity in solutions form an important tool for the evaluation of various acoustical and thermo dynamical parameters which give an insight into the nature of miscibility and molecular interactions in polymer blend. In the present investigation, ultrasonic velocities, densities and viscosities have been measured in 0.1M solution of polyvinyl chloride in tetrahydrofuran using pulse echo overlap technique at 298K at different concentrations of polyvinyl acetate. Thermoacoustical parameters such as adiabatic compressibility, molar sound velocity, molar compressibility, expansion coefficient, acoustic impedance, van der Waals' constant and internal pressure have been computed from the experimental data. The variation of ultrasonic velocity and other thermo-acoustical parameters shows nonlinear increase or decrease with molar concentration which suggest immiscibility or semi compatibility among the component polymers. Two immiscible polymers are need to be compatibilized in order to be used in commercial applications. The nature of solvent-polymer-polymer interaction and the effect of concentration on the molecular interaction of polyvinyl chloride and polyvinyl acetate in tetrahydrofuran have been studied.
Tabhane, P. V.; Chimankar, O. P.; Shriwas, R. S.; Dudhe, C. M.; Tabhane, V. A.
Composite poly(vinyl alcohol)/poly(vinyl acetate) electrospun nanofibrous mats as a novel wound dressing matrix for controlled release of drugs.
The aim of this study was to develop novel biomedicated nanofiber electrospun mats for controlled drug release, especially drug release directly to an injury site to accelerate wound healing. Nanofibers of poly(vinyl alcohol) (PVA), poly(vinyl acetate) (PVAc), and a 50:50 composite blend, loaded with ciprofloxacin HCl (CipHCl), were successfully prepared by an electrospinning technique for the first time. The morphology and average diameter of the electrospun nanofibers were investigated by scanning electron microscopy. X-ray diffraction studies indicated an amorphous distribution of the drug inside the nanofiber blend. Introducing the drug into polymeric solutions significantly decreased solution viscosities as well as nanofiber diameter. In vitro drug release evaluations showed that both the kind of polymer and the amount of drug loaded greatly affected the degree of swelling, weight loss, and initial burst and rate of drug release. Blending PVA and PVAc exhibited a useful and convenient method for electrospinning in order to control the rate and period of drug release in wound healing applications. Also, the thickness of the blend nanofiber mats strongly influenced the initial release and rate of drug release. PMID:21720511
Jannesari, Marziyeh; Varshosaz, Jaleh; Morshed, Mohammad; Zamani, Maedeh
Spectroscopic and thermal studies of PS/PVAc blends
Polystyrene and polyvinyl acetate (PS/PVAc) films were blended with different contents using casting method. The effect of PS content on PVAc blends was investigated by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Ultra violet and visible studies (UV/VIS), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Significant changes in FT-IR, XRD and DSC analysis are observed which reveals an interactions between the two polymers and PS/PVAc blends had good or certain miscibility. XRD scans show some changes in the intensity and the height of the amorphous halos with increased PS. UV/VIS analysis revealed that the optical band gap decreases with increasing content of PS from 5 to 4.11 eV. A single glass transition temperature for each blend was observed, this DSC results supported that the miscibility existed in the blend. The apparent activation energy (E) of the blends was evaluated using TGA analysis. The value of E was increased with the increase of PS content.
Elashmawi, I. S.; Hakeem, N. A.; Abdelrazek, E. M.
Toxicological Evaluation of Polyvinyl Acetate (PVA) Emulsion Dust Control Material, May 1973-March 1974.
The relative toxicity of polyvinyl acetate (PVA) emulsion dust control material was investigated using laboratory animals. PVA emulsion is a mixture composed of a base latex plasticized with cresyl diphenyl phosphate (Santicizer 140) and tetraethylene gly...
M. H. Weeks C. R. Pope
Effect of polyvinyl acetate grout injection on geotechnical properties of fine sand
This laboratory project aims to investigate the influence of polyvinyl acetate (PVA) grout injection on sandy soil improvement. In order to make the polymeric material injectable through the soil particles, adhesive polymer is mixed with water in certain weight percentages. Fine grained sand with different dry densities in its loose, medium and dense state, is prepared in a cylindrical mould
Rassoul Ajalloeian; Hossein Matinmanesh; Sayyed Mahdi Abtahi; Mohammadali Rowshanzamir
Activation Energy Spectra for Relaxation in Amorphous Materials. I. Volume Relaxation in Polystyrene and Polyvinyl Acetate
A modification of the Primak analysis for activation energy distributions is presented and compared with the well-known analysis for relaxation time distributions. Mathematical and physical interrelationships between the two analyses are discussed. Activation energy spectra are derived from the data of Kovacs for volume relaxation in polystyrene and polyvinyl acetate. The energy spectra are bell shaped and cover the range
R. M. Kimmel; D. R. Uhlmann
Decolorization of Distillery Effluent Using Poly(Vinyl Chloride) and Cellulose Acetate Phthalate as Adsorbents
Decolorization of distillery effluents, using low cost polymer adsorbents, is one of the challenging areas for environmental technologists. Untreated distillery effluents are harmful to the environment, causing foul smell, spoiling fresh water sources and killing aquatic life. The color of distillery effluents have been decolorized by using polymer based adsorbents, such as poly(vinyl chloride) (PVC) and cellulose acetate phthalate (CAP),
Valluru Ravi; Subhash Chandra Bose; T. M. Pramod Kumar; Siddaramaiah
Li ion conducting gel polymer electrolytes based on Poly(vinyl acetate)
A novel gel polymer electrolyte based on poly(vinyl acetate) and poly(vinylidene fluoride) with different plasticizers was prepared and studied by X-ray diffraction and Ac impedance methods. The blend polymer electrolyte containing propylene carbonate (PC) exhibits the highest conductivity 0.922 ū 10-2 Scm-1 at room temperature and the results were discussed.
Rajendran, S.; Mathew, Chithra M.; Marimuthu, T.; Kesavan, K.
Modification of adhesives based on poly(vinyl acetate) dispersion by the Sol-Gel method
It is shown that parameters of some properties of adhesives and adhesive joints can be increased by treating poly(vinyl acetate)\\u000a dispersion with tetraethoxysilane or ethyl silicates. It is established that the mechanism of the effect of these ethers of\\u000a orthosilicic acid are the sol-gel processes that lead to the formation of an organic-inorganic matrix.
V. A. Voitovich
Study on Preparation and Performance of Modified Polyvinyl Chloride-Co-vinyl Acetate Microfiltration Membranes
In this paper, flat-sheet microfiltration membranes were prepared from modified polyvinyl chloride-vinyl acetate (VC-co-VAc) material with hydroxyl group, VC-co-VAc-OH, by phase inversion technique. The influences of casting solution composition (polymer concentration, additive types and content) and preparation conditions (coagulation temperature, evaporation time of solvent and the relative humidity in the environment) on pure water flux, retention and pore size distribution
Jing Zhang; Wenjuan Li; Zhan Wang; Xiao Ye; Longyue Shi; Wentao Yang; Sha Chen
Vibrational and configurational heat capacity of poly(vinyl acetate) from dynamic measurements
The complex heat capacity Cp* of poly(vinyl acetate) has been measured at 20.95 mrad/s modulation frequency during the cooling as well as on heating at 24, 8, and 2 K/h and during cooling at 0.5 K/h. The study is complemented with (the rate-dependent) Cp,app measured during cooling and heating at 60, 24, and 8 K/h. At low temperatures, the real component of Cp* yields the unrelaxed Cp or Cp,vib, the vibrational part of Cp. It is found to be indistinguishable from Cp,glass and lies on a line extrapolated to its equilibrium melt's temperature. At T near Tg,?Cp(=Cp,melt-Cp,glass) shows no detectable contribution from Cp,vib. The finding conflicts with a modified entropy theory calculation [E. A. DiMarzio and F. Dowell, J. Appl. Phys. 50, 6061 (1979)], which had predicted that ~27% of ?Cp of poly(vinyl acetate) at T near Tg is vibrational in origin and the remainder configurational. At T
Tombari, E.; Ziparo, C.; Salvetti, G.; Johari, G. P.
Tombari, E.; Ziparo, C.; Salvetti, G.; Johari, G. P.
Effect of Hydroxyl Concentration on Chemical Sensitivity of Polyvinyl Alcohol/Carbon-Black Composite Chemiresistors
SciTech Connect
The sensitivity and selectivity of polyvinyl alcohol (PVA) / carbon black composite films have been found to vary depending upon the hydroxylation percentage ("-OH") of the polymer. These chemiresistors made from PVA films whose polymer backbone is 88% hydroxylated (PVA88) have a high sensitivity to water, while chemiresistors made from PVA75 have a higher sensitivity to methanol. The minor differences in polymer composition result in films with different Hildebrand volubility parameters. The relative responses of several different PVA-based chemiresistors to solvents with different volubility parameters are presented. In addition, polyvinyl acetate (PVAC) films with PVA88 are used in an array to distinguish the responses to methanol-water mixtures.
Hughes, Robert C.; Patel, Sanjay V.; Yelton, W. Graham
Evaluation of calcium alginate nasal packing (Algostķril) versus Polyvinyl acetal (Merocel) for nasal packing after inferior turbinate resection.
Nasal packing is commonly used to control postoperative bleeding in patients undergoing endonasal surgical procedures. Bleeding and pain on packing removal are frequently reported. The principal objective of this study was to investigate the efficacy and safety of Algosteril to control post-operative nasal bleeding. The secondary objective was to assess nasal bleeding and pain on packing removal, and to evaluate the endoscopic appearance of nasal mucosa 9 days after the procedure. This open, multicenter, randomized, controlled study was conducted on 50 patients undergoing partial bilateral inferior turbinectomy, packed with Algosteril on one side versus Polyvinyl acetal tampon (Merocel) on the other side following a left/right randomization. Both nasal packs effectively prevented post-operative bleeding. However, bleeding on packing removal was statistically less frequent and less severe with Algosteril than with Polyvinyl acetal (p = 0.016). In addition, pain was statistically lower with Algosteril than with Polyvinyl acetal (p = 0.0001). A trend to a better healing of the wound on day 9 was observed with Algosteril, leading us to further investigations. Algosteril nasal packing is as effective as Polyvinyl acetal in preventing postoperative bleeding following partial inferior turbinate resection. Its removal, however, is less traumatic for the nasal mucosa and less painful for the patient, therefore improving patient's comfort. PMID:16550952
Chevillard, Christine; Rugina, Michel; Bonfils, Pierre; Bougara, Ali; Castillo, Laurent; Crampette, Louis; Pandraud, Luc; Samardzic, Marina; PeynĶgre, Roger
Compatibilization by homopolymer: significant improvements in the modulus and tensile strength of PPC/PMMA blends by the addition of a small amount of PVAc.
Poly(propylene carbonate) (PPC), a polymer produced from CO2, has been melt-mixed with 30 wt % poly(methyl methacrylate) (PMMA) with the aim of enhancing the physical properties of PPC for practical use but keeping a relatively high CO2 fixing rate in the compound. The observation of a coarse phase structure with a large PMMA domain size and a large size distribution in the blend indicates the immiscibility between PPC and PMMA. The addition of a small amount of poly(vinyl acetate) (PVAc) not only shifts the glass transition temperatures (T(g)'s) of both PPC and PMMA markedly but also significantly increases the modulus and tensile strength of the blend. The prepared compound with 5 per hundred parts of resin PVAc shows a 26 times higher elastic modulus and an approximately 3.8 times higher tensile strength than pure PPC at room temperature. The morphological investigation indicates that the incorporation to PVAC not only induces the finer dispersion of PMMA in the PPC matrix but also results in the phase transformation from a sea-island to a co-continuous structure. PMID:20355779
Li, Yongjin; Shimizu, Hiroshi
Biomedical applications of stereoregular poly(vinyl alcohol) micro- and nanoparticles
Syndiotactic poly(vinyl alcohol) (PVA)/poly(vinyl pivalate/vinyl acetate) (P(VPi/VAc)) and atactic PVA/PVAc micro- and nanoparticles with skin/core structure have been prepared by heterogeneous saponification of P(VPi/VAc) and PVAc micro- and nanoparticles. Especially, to prepare P(VPi/VAc) and PVAc microparticles having various particle sizes and uniform particle size distribution, vinyl pivalate (VPi)/vinyl acetate (VAc) and VAc were suspension-polymerized using a low-temperature initiator, 2,2"-azobis(2,4-dimethylvaleronitrile). P(VPi/VAc) particles are promising precursor of stereoregular PVA embolic materials which can be introduced through catheters in the management of gastrointestinal bleeders, arteriovenous malformations, hemangiomas, and traumatic rupture of blood vessels. Monodisperse and/or nearly monodisperse P(VPi/VAc) and PVAc microparticles with various particle diameters were obtained by controlling suspension polymerization conditions. Monodisperse P(VPi/VAc) and PVAc microparticles having various particle sizes were partially saponified in the heterogeneous system. PVA/P(VPi/VAc) and PVA/PVAc microparticles having various tacticity and degree of saponification were produced by controlling various polymerization and saponification conditions. The coating of stereoregular PVA micro- and nanoparticles for drug release experiments was conducted with the strepo-avidin-alkaline phosphatase conjugate in variable conditions of pH value, coating buffer, and reaction temperature. Protein-coated syndiotactic PVA micro- and nanoparticles, which does not crosslinking, were more superior to controllability of drug release, durability, and dimensional stability to water and blood than atactic one.
Lyoo, Won Seok; Kim, Joon Ho; Kim, Sam Soo; Ghim, Han Do
Effects of vibration technology and polyvinyl acetate emulsion on microstructure and properties of expanded polystyrene lightweight concrete
To prevent expanded polystyrene (EPS) beads from rising up to the surface in the molding process of EPS lightweight concrete,\\u000a vibration with pressure was applied and the polyvinyl acetate (PVA) emulsion was adopted to improve its mechanical properties.\\u000a The mechanical properties, thermal properties and durability of EPS lightweight concrete were tested. The microstructures\\u000a of EPS lightweight concrete were observed by
Xiaoyan Zhao; Wenling Tian; Xinliang Jiang; Xuesong Zhang
Preparation and study of poly(vinyl acetate) and poly(styrene) nanosized latex with indometacin.
During the last decade the number of investigations on the preparation and application of more effective drug release systems on the basis of nanocarriers from biocompatible and biodegradable polymers are considerably increasing. This is notably in force for practically water insoluble drugs to be applied in liquid forms (eye solutions for an example). The aim of the work presented was the preparation of model poly(vinyl acetate) and poly(styrene) nanosupports for indometacin and their potential inclusion in eye drops. The polymers are synthesized as nanosized latex by a radical polymerization of the monomers in the presence of indometacin. It is proved that the low polymerization temperature and initiator used do not influence indometacin structure and properties. The nanoparticles were characterized by attenuated total reflection Fourier transform infrared spectroscopic analyses, atomic force microscopy, scanning electron microscopy and transmission electron microscopy. The size of the latex particles was around 200 nm, determined by the scan electron microscopy. The indometacin delivery rate from the supports discussed in aqueous solutions was determined at pH 7.4. The change of this rate, in comparison with that for a pure drug substance, was established also as well as its dependence on the nature of the carrier. PMID:22888516
Andonova, V; Georgiev, G; Toncheva, V; Kassarova, M
Evaluation of polyvinyl acetate dispersion as a sustained release polymer for tablets.
Kollicoat SR 30D is a unique 30% aqueous dispersion of polyvinvyl acetate stabilized by polyvinyl-pyrrolidone intended for preparation of sustained release products. Detailed evaluation of this polymer dispersion as a sustained release coating for active pharmaceutical ingredients of two diverse classes of drugs was studied. A water insoluble drug (ibuprofen) and a water soluble drug (ascorbic acid) were selected as model active drugs. Ibuprofen was granulated using a GPCG-1 fluid bed processor prior to tableting, to improve the particle size and particle flow properties. In this process a 2(3) factorial design was implemented to evaluate the optimum process parameters such as spray rate, inlet air temperature and the inlet air velocity. The statistical model selected was Y(ijkl) = mu + tau(i) + beta(j) + theta(k) + (taubeta)ij + (betatheta)jk + (tautheta)ik + (taubetatheta)ijk + epsilon(ijkl). The factorial design showed that the spray rate, inlet air temperature, and inlet air velocity had a significant effect (p value <0.05) on the particle size. Significant improvement was observed in the flow properties of the granules. The granules were coated with Kollicoat SR30D dispersion using top spray method in the fluid bed processor. The dissolution studies showed that the release of ibuprofen decreased with an increase in the coating levels of Kollicoat SR 30 D. In the case of ascorbic acid, preparation of sustained release coated commercial granules was not possible due to the difficulty in coating a highly soluble drug particle. However, the coated granules when compressed into tablets showed some sustainability. Ibuprofen tablets manufactured with coated granules with a 15 g polymer for 300 g batch showed dissolution parameters of t50 and t90 at 4.2 hr and 7.5 hr, respectively. An approximate zero-type of release was observed when the polymer content was increased to 45 g for 300 g batch. Ascorbic acid tablets made with coated commercial granules having a total polymer content of 45 g per a 500 g batch showed an average dissolution t50 and t90 at 1.0 hr and 4.55 hr, respectively. When the total polymer content was increased to 60 g, per 500 g, the average dissolution t50 and t90 delayed to 1.40 hr and 7.20 hr, respectively. PMID:16423800
Bordaweka, M S; Zia, H; Quadir, A
Effect of poly(vinyl acetate-acrylamide) microspheres properties and steric hindrance on the immobilization of Candida rugosa lipase.
Poly(vinyl acetate-acrylamide) microspheres were synthesized in the absence or presence of isooctane via suspension polymerization and utilized as carriers to immobilize Candida rugosa lipase. When the hydrophobic/hydrophilic surface characteristics of the microspheres were modified by changing the ratio of vinyl acetate (hydrophobic monomer) to acrylamide (hydrophilic monomer) from 50:50 to 86:24, the immobilization ratio changed from 45% to 92% and the activity of the immobilized lipase increased from 202.5 to 598.0 U/g microsphere. Excessive lipase loading caused intermolecular steric hindrance, which resulted in a decline in lipase activity. The maximum specific activity of the immobilized lipase (4.65 U/mg lipase) was higher than that of free lipase (3.00 U/mg lipase), indicating a high activity recovery during immobilization. PMID:22989650
Zhang, Dong-Hao; Yuwen, Li-Xia; Li, Chao; Li, Ya-Qiong
Microwave irradiation induced modifications on the interfaces in SAN/EVA/PVC and PVAc/BPA/PVP ternary polymer blends: Positron lifetime study
Ternary polymer blends of poly(styrene-co-acrylonitrile)/poly(ethylene-co-vinylacetate)/poly(vinyl chloride) (SAN/EVA/PVC) and poly(vinyl acetate)/bisphenol A/polyvinylpyrrolidone (PVAc/BPA/PVP) with different compositions have been prepared by solvent casting method and characterized by positron lifetime spectroscopy and differential scanning calorimetry DSC. Phase modifications have been induced by irradiating the blends with microwave radiation. These changes have been monitored by measuring the free-volume content in the blends. The results clearly show improved interactions between the constituent polymers of the blends upon microwave irradiation. However, the free-volume data and DSC measurements are found to be inadequate to reveal the changes at the interfaces and the interfaces determine the final properties of the blend. For this we have used hydrodynamic interaction (?ij) approach developed by us to measure strength of hydrodynamic interaction at the interfaces. These results show that microwave irradiation stabilizes the interfaces if the blend contains strong polar groups. SAN/EVA/PVC blend shows an increased effective hydrodynamic interaction from -3.18 to -4.85 at composition 50/35/15 upon microwave irradiation and PVAc/BPA/PVP blend shows an increased effective hydrodynamic interaction from -3.81 to -7.57 at composition 20/50/30 after irradiation.
Dinesh, Meghala; Chikkakuntappa, Ranganathaiah
Polyvinyl Alcohol Hydrogel Irradiated and Acetalized for Osteochondral Defect Repair: Mechanical, Chemical, and Histological Evaluation after Implantation in Rat Knees
PubMed Central
Polyvinyl Alcohol (PVA) hydrogel plugs were implanted in artificial osteochondral defects on the trochlear groove of rat knees. After 0, 3, 6, 12, and 24 weeks of followup, samples containing the implants were mechanically evaluated by creep indentation test, chemically, and histologically by optical microscopy. The mechanical test pointed towards an increase of the implant creep modulus and the chemical analysis exhibited an increasing concentration of calcium and phosphorus within the implants over time. Optical microscopy showed no foreign body reaction and revealed formation, differentiation, and maintenance of new tissue at the defect/implant interface. The absence of implant wear indicated that the natural articular lubrication process was not disturbed by the implant. The performance of the irradiated and acetalized PVA was considered satisfactory for the proposed application.
Batista, N. A.; Rodrigues, A. A.; Bavaresco, V. P.; Mariolani, J. R. L.; Belangero, W. D.
Solubilities of crystalline drugs in polymers: an improved analytical method and comparison of solubilities of indomethacin and nifedipine in PVP, PVP/VA, and PVAc.
A previous method for measuring solubilities of crystalline drugs in polymers has been improved to enable longer equilibration and used to survey the solubilities of indomethacin (IMC) and nifedipine (NIF) in two homo-polymers [polyvinyl pyrrolidone (PVP) and polyvinyl acetate (PVAc)] and their co-polymer (PVP/VA). These data are important for understanding the stability of amorphous drug-polymer dispersions, a strategy actively explored for delivering poorly soluble drugs. Measuring solubilities in polymers is difficult because their high viscosities impede the attainment of solubility equilibrium. In this method, a drug-polymer mixture prepared by cryo-milling is annealed at different temperatures and analyzed by differential scanning calorimetry to determine whether undissolved crystals remain and thus the upper and lower bounds of the equilibrium solution temperature. The new annealing method yielded results consistent with those obtained with the previous scanning method at relatively high temperatures, but revised slightly the previous results at lower temperatures. It also lowered the temperature of measurement closer to the glass transition temperature. For D-mannitol and IMC dissolving in PVP, the polymer's molecular weight has little effect on the weight-based solubility. For IMC and NIF, the dissolving powers of the polymers follow the order PVP > PVP/VA > PVAc. In each polymer studied, NIF is less soluble than IMC. The activities of IMC and NIF dissolved in various polymers are reasonably well fitted to the Flory-Huggins model, yielding the relevant drug-polymer interaction parameters. The new annealing method yields more accurate data than the previous scanning method when solubility equilibrium is slow to achieve. In practice, these two methods can be combined for efficiency. The measured solubilities are not readily anticipated, which underscores the importance of accurate experimental data for developing predictive models. PMID:20607809
Sun, Ye; Tao, Jing; Zhang, Geoff G Z; Yu, Lian
Viscometric investigation of compatibilization of the poly(vinyl chloride)/poly(ethylene-co-vinyl acetate) blends by terpolymer of maleic anhydride styrene vinyl acetate
In this study, a blend of poly(vinyl chloride) (PVC)/ethylene-co-vinyl acetate (EVA) was compatibilized by terpolymer of maleic anhydride-styrene-vinyl acetate (MAStVA) used as a compatibilizer. It was prepared the blends of 50/50 PVC/EVA containing 2-10% of the terpolymer. The compatibility experiences of these blends were investigated by using viscometric method in the range of concentrations (0.5-2.0 g dL -1) where tetrahydrofuran (THF) is the solvent. The interaction parameter (? b) was used to study the miscibility and compatibility of polymer blend in solution, obtained from the modified Krigbaum and Wall theory. Turbidity and FTIR measurements were also used to investigate the miscibility of this pair of polymers. The values of the relative viscosities of the each polymer solution and their blends were measured by a Cannon-Fenske type viscometer. In consequence of the study, it was observed that a considerable improvement was achieved in the miscibility of PVC/EVA blends by adding among 5 and 10 wt% of compatibilizer.
?mren, Dilek; Boztu?, Ali; Y?lmaz, Ersen; Zengin, H. Bayram
Photo-Fries rearrangements of 1-naphthyl (R)-2-phenylpropanoate in poly(vinyl acetate) and ethyl acetate: influence of medium polarity and polymer relaxation on motions of singlet radical pairs
Both the regio- and stereo-chemistries of the photoreactions of 1-naphthyl (R)-2-phenylpropanoate have been investigated in poly(vinyl acetate) films in their glassy (at 5 ? C) and melted (at 50 ? C) states and in ethyl acetate. These results are compared with those from irradiations in polyethylene films and in n-hexane. The regioselectivity of the intermediate 1-naphthoxy\\/(R)-2-phenylpropanoyl radical pair combinations is
Jinqi Xu; Mathew George; Richard G. Weiss
Optimization of tribological and mechanical properties of nanocomposites of polyurethane/poly(vinyl acetate)/CaCO3.
Properties of samples containing polyurethane (PU), poly(vinyl acetate) (PVAc) and nanosize particles of calcium carbonate (CaCO3) are correlated with concentrations of these components. Interphase phenomena in PU/PVAc/CaCO3 nanohybrids have been studied before, we focus here on wear and scratch resistance. In addition to polymer blends containing CaCO3, the effects of adding CaCO3 with grafted PVAc, and CaCO3 with grafted silane and PVAc in varying ratios are also evaluated. For blends that do not contain the filler, a hypothesis explaining the concentration dependence of friction called the Bump Model is advanced and supported by the experimental results. In particular, we explain how creating a blend containing only 10% of a second polymer results in a dramatic drop of friction of the majority polymer. In single scratch testing, above 3% the filler displays 'its own' resistance to scratching. Chemical modification of the filler results in shallower residual depths--a consequence of improved interaction of the filler with the polymeric matrix. In sliding wear determination, strain hardening is seen for blends as well as for filler-containing composites. In tensile testing, addition of an unmodified filler increases the elongation at break and thus lowers the brittleness; the effect is even larger for chemically modified fillers. PMID:21780387
Brostow, Witold; Kumar, Puneet; Vrsaljko, Domagoj; Whitworth, Jenna
Photo-Fries rearrangements of 1-naphthyl (R)-2-phenylpropanoate in poly(vinyl acetate) and ethyl acetate. Influence of medium polarity and polymer relaxation on motions of singlet radical pairs.
Both the regio- and stereo-chemistries of the photoreactions of 1-naphthyl (R)-2-phenylpropanoate have been investigated in poly(vinyl acetate) films in their glassy (at 5 degrees C) and melted (at 50 degrees C) states and in ethyl acetate. These results are compared with those from irradiations in polyethylene films and in n-hexane. The regioselectivity of the intermediate 1-naphthoxy/(R)-2-phenylpropanoyl radical pair combinations is much higher in both the melt and glassy states of poly(vinyl acetate) films than that in the melt state of completely amorphous polyethylene films, but the stereoselectivity of intermediate prochiral 1-naphthoxy/1-phenylethyl radical pair combinations is much lower in poly(vinyl acetate). The results emphasize the need to control the ratio between the rates of radical tumbling and translation, as well as the ratio between the rates of in-cage motions and cage-escape, if high stereo- and regio-selectivities of combination products are to be achieved. A mechanistic picture of how the radicals of the intermediate pairs are affected by and interact with the various media is advanced. PMID:16532205
Xu, Jinqi; George, Mathew; Weiss, Richard G
A DSC study of poly(styrene-co-acrylonitrile) and poly(vinyl chloride-co-vinyl acetate) blends produced using different blending techniques
Comparative and comprehensive studies of poly(styrene-co-acrylonitrile) (SAN) and poly(vinyl chloride-co-vinyl acetate) (VYHH) blends using several blending techniques such as melt-mixing, solution blending and co-precipitation methods by an appropriate non-solvent were performed. The compatibility of the blends was studied by measuring the glass-transition temperatures (Tgs) of the blends and also by measuring the heat capactiy change (?Cp) at the glass transition
Gaurab Das; Amar Nath Banerjee; B. C. Mitra
Permeation and Separation Characteristics of Acetic Acid?Water Mixtures Through Poly(Vinyl Alcohol)\\/Malic Acid Membranes by Evapomeation and Temperature Difference Controlled Evapomeation
The characteristics of permeation and separation of acetic acid?water mixtures through 85\\/15 (v\\/v) poly(vinyl alcohol)\\/malic acid (PVA\\/MA) membranes were investigated by evapomeation (EV) and temperature difference controlled evapomeation (TDEV) methods. The effects of permeation temperature, membrane surrounding temperature, and feed composition on the permeation rate and the separation factor were studied. The permeation rates increased but separation factors decreased with
Nuran I??klan; Oya ?anl?
Comparative Study on the Efficacy of Gingival Retraction using Polyvinyl Acetate Strips and Conventional Retraction Cord - An in Vivo Study.
Statement of Problem: A new material is proposed in dentistry in the form of strips for producing gingival retraction. The clinical efficacy of the material remains untested. Purpose of the Study: This study aimed to determine whether the polyvinyl acetate strips are able to effectively displace the gingival tissues in comparison with the conventional retraction cord. Material and Methods: Complete metal ceramic preparation with supra-gingival margin was performed in fourteen maxillary incisors and gingival retraction was done using Merocel strips and conventional retraction cords alternatively in 2 weeks time interval. The amount of displacement was compared using a digital vernier caliper of 0.01mm accuracy. Results were analyzed statistically using Paired students t-test. Results: The statistical analysis of the data revealed that both the conventional retraction cord and the Merocel strip produce significant retraction. Among both the materials, Merocel proved to be significantly more effective. Conclusion: Merocel strip produces more gingival displacement than the conventional retraction cord. PMID:24298531
Shivasakthy, M; Asharaf Ali, Syed
Anion recognition using newly synthesized hydrogen bonding disubstituted phenylhydrazone-based receptors: poly(vinyl chloride)-based sensor for acetate.
A potentiometric acetate-selective sensor, based on the use of butane-2,3-dione,bis[(2,4-dinitrophenyl)hydrazone] (BDH) as a neutral carrier in poly(vinyl chloride) (PVC) matrix, is reported. Effect of various plasticizers and cation excluder, cetryaltrimethylammonium bromide (CTAB) was studied. The best performance was obtained with a membrane composition of PVC:BDH:CTAB ratio (w/w; mg) of 160:8:8. The sensor exhibits significantly enhanced selectivity toward acetate ions over a wide concentration range 5.0 x 10(-6) to 1.0 x 10(-1)M with a lower detection limit of 1.2 x 10(-6)M within pH range 6.5-7.5 with a response time of <15s and a Nernstian slope of 60.3+/-0.3 mV decade(-1) of activity. Influences of the membrane composition, and possible interfering anions were investigated on the response properties of the electrode. Fast and stable response, good reproducibility and long-term stability are demonstrated. The sensor has a response time of 15s and can be used for at least 65 days without any considerable divergence in their potential response. Selectivity coefficients determined with the separate solution method (SSM) and fixed interference method (FIM) indicate that high selectivity for acetate ion. The proposed electrode shows fairly good discrimination of acetate from several inorganic and organic anions. It was successfully applied to direct determination of acetate within food preservatives. Total concentration of acetic acid in vinegar samples were determined by direct potentiometry and the values agreed with those mentioned by the manufacturers. PMID:18656670
Gupta, Vinod K; Goyal, Rajendra N; Sharma, Ram A
Physicochemical and release properties of pellets coated with Kollicoat SR 30 D, a new aqueous polyvinyl acetate dispersion for extended release.
Kollicoat SR 30 D is a new aqueous colloidal polyvinyl acetate dispersion used for extended release coatings. Kollicoat SR 30 D is stable against sedimentation, has a low viscosity (54 mPas) and a negative zeta potential of -23.2 mV because of the presence of the anionic surfactant, sodium dodecyl sulfate. Because of its low minimum film formation temperature (MFT = 18 degrees C), plasticizer addition and a thermal after-treatment (curing) of coated pellets was not required. Coated pellets showed no aging or curing effect. The rate of release could be easily adjusted by varying the coating level. A subcoating layer of the hydrophilic polymer, polyvinyl alcohol, between an ibuprofen-containing core and the Kollicoat SR coating prevented the diffusion of the lipophilic, low melting ibuprofen into the polymer coating during storage. The drug release from Kollicoat SR 30 D coated pellets was almost independent of the pH and ionic strength of release medium. PMID:15664126
Dashevsky, A; Wagner, K; Kolter, K; Bodmeier, R
Preparation and characterization of poly(vinyl chloride-co-vinyl acetate)-based gel electrolytes for Li-ion batteries
Poly(vinyl chloride) (PVC)-based electrolytes, a class of the most promising polymer electrolytes, are found to suffer from solvent exudation. Two strategies were employed to suppress this shortcoming, one involving the replacement of PVC with poly(vinyl chloride-co-vinyl acetate) (PVCAC) copolymer and the other the direct utilization of solvents for PVC or PVCAC instead of using an auxiliary carrier solvent (e.g., tetrahydrofuran, THF). The thermodynamics of polymer solubility was particularly emphasized in the latter approach. N,N-dimethylformamide (DMF) and N-methyl pyrrolidionone (NMP) are preferred cosolvents of ethylene carbonate (EC) and/or propylene carbonate (PC). The PVCAC-based gel electrolytes prepared were then characterized by ionic conductivity, cyclic voltammetry, and ac impedance data. The results indicate that electrolytes containing NMP/EC mixed solvent exhibit conductivities exceeding 10{sup {minus}3} S/cm whereas the electrolytes containing DMF/EC/PC exhibit conductivities around 10{sup {minus}4} S/cm at room temperature. Moreover, the former category was found to be oxidatively stable up to 4.9 V vs. Li/Li{sup +} and the latter to 4.6 V vs. Li/Li{sup +}. Finally, ac impedance results suggest that the stability of the Li/electrolyte interface needs further improvement, which is a crucial task for most polymer gel electrolytes at present.
Sung, H.Y.; Wang, Y.Y.; Wan, C.C. [National Tsing-Hua Univ., Hsinchu (Taiwan, Province of China). Dept. of Chemical Engineering
Response to ``Comment on `Temperature divergence of the dynamics of a poly(vinyl acetate) glass: Dielectric vs. mechanical behaviors''' [J. Chem. Phys. 139, 137101 (2013)
R. Richert has made a comment to a paper of ours in which dielectric measures on poly(vinyl acetate) suggest that there is a change in temperature dependence of the temperature shift factors from Vogel-Fulcher-Tammann (VFT) to Arrhenius near to the glass transition temperature. He notes that we made an error in the description of his data and further notes that the data we did not use show a VFT behavior to well below the glass transition. Here we respond to the comment and add additional analysis that suggest that the differences in results are related to the differences between time temperature superposition (TTS) of data and fitting the data with a Kohlrausch, Williams, and Watts function. When TTS is used on the data from Wagner and Richert [Polymer 38, 255 (1997)] the change in behavior to Arrhenius-like below Tg is recovered.
Zhao, Jing; McKenna, Gregory B.
Monodisperse porous poly(vinyl acetate-co-divinylbenzene) particles by single-stage seeded polymerization: a packing material for reversed phase HPLC.
A single-stage swelling and polymerization method was proposed for the synthesis of monodisperse porous poly(vinyl acetate-co-divinylbenzene) [poly(VAc-co-DVB)] particles with different VAc/DVB feed ratios. The particles obtained with the VAc/DVB feed ratio of 50:50 v/v had a narrow pore size distribution exhibiting a sharp peak at 30 nm. Based on this distribution the mean pore size and the specific volume were determined as 12 nm and 1.39 mL/g, respectively. The specific surface area of poly(VAc-co-DVB) particles was found to be 470 m2/g. These properties make poly(VAc-co-DVB) particles a promising support for potential HPLC applications. Poly(vinyl alcohol-co-divinylbenzene) [poly(VA-co-DVB)] particles were then obtained by the basic hydrolysis of poly(VAc-co-DVB) particles. The hydroxyl groups on poly(VA-co-DVB) particles have a suitably reactive functionality for surface grafting or derivatization protocols aiming at synthesizing various HPLC packings. The examination of poly(VA-co-DVB) particles by confocal laser scanning microscopy showed the homogeneous distribution of hydroxyl functionality in the particle interior. As a starting point, the chromatographic performance of plain material, poly(VAc-co-DVB) particles produced with VAc/DVB feed ratio of 50:50 (v/v) was tested by a commonly utilized chromatographic mode, reversed phase chromatography. Poly(VAc-co-DVB) particles were successfully used as packing material in the RP separation of alkylbenzenes with resolutions higher than 1.5. Theoretical plate numbers up to 17 500 plates/m were achieved. No significant change both in the chromatographic resolution and column efficiency was observed with increasing flow rate. The chromatography showed that poly(VAc-co-DVB) particles were a suitable starting material for the synthesis of chromatographic packings for different modes of HPLC. PMID:16833225
Caglayan, Berna; Unsal, Ender; Camli, S Tolga; Tuncel, Murvet; Tuncel, Ali
Synthesis of poly(vinyl acetate) with fluorescence via a combination of RAFT\\/MADIX and ōclickö chemistry
A novel ?-azido-functionalized RAFT reagent, O-(2-azido-ethyl) S-benzyl dithiocarbonate (AEBDC), was synthesized and subsequently employed to mediate the reversible addition¢fragmentation chain transfer (RAFT) polymerization of vinyl acetate (VAc) to prepare end-functionalized polymers. The polymerization results showed that the RAFT polymerizations of VAc could be well controlled using AEBDC as the RAFT agent. Number-average molecular weights (MnGPC) increased linearly with monomer conversion,
Fen Chen; Zhenping Cheng; Jian Zhu; Wei Zhang; Xiulin Zhu
Compatibilization of immiscible poly(vinyl chloride) (PVC)/polystyrene (PS) blends with maleic anhydride-styrene-vinyl acetate terpolymer (MAStVA)
In this study, compatibilizing effects of maleic anhydride-styrene-vinyl acetate (MAStVA) with various terpolymer ratios on immiscible blends of poly(vinyl chloride) (PVC) and polystyrene (PS) blends were investigated by viscometry method, thermo-mechanical analysis (TMA) and infrared spectroscopy (FTIR). The viscosimetric measurements were carried out for PVC, PS, a (70:30) blend of PVC/PS and a blend of PVC/PS/MAStVA containing 2-10% of the terpolymer in the range of concentrations (0.25-2.00 g dL -1) where tetrahydrofuran (THF) is the solvent. The interaction parameter (? b) was used to study the miscibility and compatibility of polymer blend in solution, obtained from the modified Krigbaum and Wall theory. TMA and FTIR measurements were also used to investigate the miscibility of this pair of polymers. In consequence of the study, it was observed that a considerable improvement was achieved in the miscibility of PVC/PS blends by adding among 4 and 10 wt.% of compatibilizer.
?mren, Dilek
A case-controlled, retrospective, comparative study on the use of biodegradable synthetic polyurethane foam versus polyvinyl acetate sponge after nasal fracture reduction.
One of the most frequently used packing materials in closed reduction of a nasal bone fracture is the hydroxylated polyvinyl acetate sponge (PVAS; Merocel(«)); however this may cause synechia, epistaxis, and pain. Synthetic polyurethane foam (SPF; Nasopore(«) Forte) has recently been used in septoplasty to prevent synechia or restenosis and haematoma formation. The purpose of this study was to compare the effects of PVAS and SPF on postoperative appearance and discomfort following the reduction of nasal bone fractures. We retrospectively reviewed all patient questionnaires and medical histories, and clinical photographs and computed tomography scans obtained before and after surgery. Outcomes were assessed using the Global Aesthetic Improvement Scale (GAIS) score and visual analogue scale (VAS) scores, which were used to assess discomfort during the 6-month follow-up period. Postoperatively, there was no statistically significant difference in the GAIS for the two packing materials (P>0.05). Postoperative epistaxis was observed at a significantly lower rate in the SPF group than in the PVAS group, whereas anterior rhinorrhea and posterior nasal drip occurred at significantly higher rates following removal of packing in the SPF group (P<0.05). The results of this study suggest that synthetic dissolvable polyurethane may be a reliable alternative material for nasal packing and postoperative management following the reduction of nasal bone fractures. PMID:24613644
Jeong, H-S; Lee, H-K; Kim, H-S; Moon, M-S; Tark, K-C
Development of poly(vinyl acetate-methylacrylic acid)/chitosan/Fe3O4 nanoparticles for the diagnosis of non-alcoholic steatohepatitis with magnetic resonance imaging.
Non-alcoholic steatohepatitis is a burgeoning health problem. To diagnose NASH with magnetic resonance imaging (MRI), an effective contrast agent, a stable suspension of superparamagnetic Fe(3)O(4) nanoparticles, were newly developed. The negatively charged Fe(3)O(4) nanoparticles were coated with positive chitosan (CS) firstly, and then assembled with poly(vinyl acetate-methylacrylic acid) (P(VAc-MAA)). Transmission electron microscope and dynamic light scattering confirmed that the obtained P(VAc-MAA)/CS/Fe(3)O(4) nanoparticles had a spherical or ellipsoidal morphology with an average diameter in the range of 14-20 nm. The superparamagnetic property and spinel structure of the Fe(3)O(4) nanoparticles were well preserved due to the protection of the P(VAc-MAA)/CS layers on the surface of the Fe(3)O(4) nanoparticles. The in vivo rat experiments confirmed that the P(VAc-MAA)/CS/Fe(3)O(4) nanoparticles were an effective contrast agent for MRI to diagnose NASH. PMID:22976475
Luo, Xiadan; Song, Xiaoli; Zhu, Aiping; Si, Yunfeng; Ji, Lijun; Ma, Zhanrong; Jiao, Zhiyun; Wu, Jingtao
Safety of PVAP and PVAP-T including a 90-day dietary toxicity study in rats and genotoxicity tests with polyvinyl acetate phthalate (PVAP).
The safety of PVAP was evaluated in a 90-day subchronic toxicity study in rats. Sprague Dawley Crl:CD(SD) rats were administered a dietary concentration of 0.75%, 1.5% and 5.0% PVAP for a minimum of 90days. There were no adverse effects reported. The no-observed-adverse-effect level (NOAEL) in the 90-day sub chronic study was the 5% dietary concentration, which corresponds to a dose of 3120mg/kg/day for males and 3640mg/kg/day for females, the highest level tested. PVAP is co-processed with titanium dioxide to produce polyvinyl acetate phthalate and titanium dioxide (PVAP-T). The chemical composition, physiochemical properties and specifications of PVAP-T are unchanged during manufacturing process based on various analytical studies. Therefore, the toxicological data that support the safety of PVAP can be used to support the use of PVAP-T as a pharmaceutical excipient. An independent expert panel evaluated the safety of PVAP and PVAP-T. Based on the toxicology study results, safety assessment and the estimated exposure assessment for PVAP and PVAP-T, the expert panel concluded that PVAP and PVAP-T could safely be used in drug products up to 829mg per day which was the estimated exposure provided to the expert panel for current applications of PVAP and PVAP-T. PMID:24813760
DeMerlis, C C; Schoneker, D R; Borzelleca, J F
Estimation of polyvinyl alcohol cryogel mechanical properties with four ultrasound elastography methods and comparison with gold standard testings
Tissue-mimicking phantoms are very useful in the field of tissue characterization and essential in elastography for the purpose of validating motion estimators. This study is dedicated to the characterization of polyvinyl alcohol cryogel (PVA-C) for these types of applications. A strict fabrication procedure was defined to optimize the reproducibility of phantoms having a similar elasticity. Following mechanical stretching tests, the
Jeremie Fromageau; Jean-Luc Gennisson; Cedric Schmitt; Roch L. Maurice; Rosaire Mongrain; G. Cloutier
Modifying the MRI, elastic stiffness and electrical properties of polyvinyl alcohol cryogel using irradiation
The aim of this work was to study the effect of radiation on the elastic stiffness, electrical and MRI properties of polyvinyl alcohol (PVA)-based cryogel (PVA-C). The PVA-C samples were irradiated with a 60C0 ?-source, at 2.18 ū 10 6 Rads. The indentation measurements (an indication of elastic stiffness) reduced by about 14.6% for PVA-3C and 5.7% PVA-6C after irradiation, indicating that the material became harder/stiffer. It was found that MRI relaxation times provide an alternative and non-destructive method to evaluate the radiation effect on PVA-C. The T1 of PVA-C that had undergone three freeze thaw cycles decreased with irradiation by 10%, 25% and 35% at 1 T, 1.89 T and 3 T respectively. The T1 of PVA-C that had undergone six freeze thaw cycles decreased with irradiation by 18%, 15% and 11% at 1 T, 1.89 T and 3 T respectively. The T2 of PVA-C decreased with irradiation only at 1 T, however this change is hypothesized to be due to the interaction of two spin pools in the gel. The electrical conductivity ( ?) and permittivity constant ( ?) of the unirradiated and ?-irradiated PVA-C samples were measured at different frequencies in the range 40 Hz to 1 MHz. The results demonstrated that the conductivity increased with irradiation by 50% for PVA-3C (three freeze thaw cycles) and 75% for PVA-6C (six freeze thaw cycles) at frequencies greater than 1 KHz.The permittivity decreased with irradiation up to 25% for 3C and 35% for 6C at frequencies less than 1 KHz.
Goharian, Mehran; Moran, Gerald R.; Wilson, Kyle; Seymour, Colin; Jegatheesan, Aravinthan; Hill, Michael; Thompson, R. Terry; Campbell, Gordon
Cellulose whiskers reinforced polyvinyl alcohol copolymers nanocomposites
Nanocomposite materials were prepared from copolymers of polyvinyl alcohol and polyvinyl acetate and a colloidal aqueous suspension of cellulose whiskers prepared from cotton linter. The degree of hydrolysis of the matrix was varied in order to vary the hydrophilic character of the polymer matrix and then the degree of interaction between the filler and the matrix. Nanocomposite films were conditioned
Mehdi Roohani; Youssef Habibi; Naceur M. Belgacem; Ghanbar Ebrahim; Ali Naghi Karimi; Alain Dufresne
Primary Plasticizers for Poly(Vinyl Chloride).
According to the patent application, acetal derivatives of polyunsaturated fatty compositions were prepared and found to function as primary plasticizers. Poly(vinyl chloride) resins plasticized by the compositions of this application have properties equa...
R. A. Awl E. H. Pryde
Poly(vinyl alcohol) cryogel, multi-layer artery phantoms for optical coherence tomography
In this paper, we present recent development of phantoms of coronary arteries with representative mechanical properties. The phantoms were made of poly(vinyl alcohol) cryogel (PVA-C). Multilayer phantoms were fabricated by an overmoulding process. The optical properties are adjusted in each layer by the different number of freeze-thaw cycles in combination with additives. The mechanical properties of the multilayer phantoms are characterized, and various means for improving the strain hardening are investigated.
Bisaillon, Charles-Etienne; Campbell, Gordon; Pazos, Valķrie; Lamouche, Guy
Poly(vinyl alcohol) cryogel phantoms for use in ultrasound and MR imaging
Poly(vinyl alcohol) cryogel, PVA-C, is presented as a tissue-mimicking material, suitable for application in magnetic resonance (MR) imaging and ultrasound imaging. A 10% by weight poly(vinyl alcohol) in water solution was used to form PVA-C, which is solidified through a freeze-thaw process. The number of freeze-thaw cycles affects the properties of the material. The ultrasound and MR imaging characteristics were investigated using cylindrical samples of PVA-C. The speed of sound was found to range from 1520 to 1540 m s-1, and the attenuation coefficients were in the range of 0.075-0.28 dB (cm MHz)-1. T1 and T2 relaxation values were found to be 718-1034 ms and 108-175 ms, respectively. We also present applications of this material in an anthropomorphic brain phantom, a multi-volume stenosed vessel phantom and breast biopsy phantoms. Some suggestions are made for how best to handle this material in the phantom design and development process.
Surry, K. J. M.; Austin, H. J. B.; Fenster, A.; Peters, T. M.
Complex AC impedance, transference number and vibrational spectroscopy studies of proton conducting PVAc-NH 4SCN polymer electrolytes
The polymer electrolytes composed of poly (vinyl acetate) (PVAc) with various stoichiometric ratios of ammonium thiocyanate (NH 4SCN) salt have been prepared by solution casting method. The polymer-salt complex formation and the polymer-proton interactions have been analysed by FT-IR spectroscopy. The conductivity and dielectric measurements are carried out on these films as a function of frequency at various temperatures. The complex impedance spectroscopy results reveal that the high-frequency semicircle is due to the bulk effect of the material. The conductivity is found to increase in the order of 10 -8-10 -4 S cm -1 at 303 K with the increase in salt concentration. The ionic transference number of mobile ions has been estimated by Wagner's polarization method and the results reveal that the conducting species are predominantly due to ions. The transient ionic current (TIC) measurement technique has been used to detect the type of mobile species and to evaluate their mobilities. The dielectric spectra show the low-frequency dispersion, which is due to the space charge effects arising from the electrodes.
Selvasekarapandian, S.; Baskaran, R.; Hema, M.
In situ Self Cross-Linking of Polyvinyl Alcohol Battery Separators.
The method disclosed is used to produce a polyvinyl alcohol sheet material wherein the polyvinyl alcohol is substantially free of 1,2 diol units, and has an acetal self cross-linked structure wherein the acetal content is determined by the 1,2 diol conten...
W. H. Philipp L. C. Hsu D. W. Sheibley
Preparation and properties of poly(vinyl alcohol)/chitosan blend bionanocomposites reinforced with cellulose nanocrystals/ZnO-Ag multifunctional nanosized filler.
A series of novel bionanocomposites were cast using different contents of zinc oxide-silver nanoparticles (ZnO-AgNPs) stabilized by cellulose nanocrystals (CNC) as multifunctional nanosized fillers in poly(vinyl alcohol)/chitosan (PVA/Cs) matrices. The morphological structure, mechanical properties, ultraviolet-visible absorption, and antimicrobial properties of the prepared films were investigated as a function of their CNC/ZnO-AgNP content and compared with PVA/chitosan/CNC bionanocomposite films. X-ray diffraction and field emission scanning electron microscopic analyses showed that the CNC/ZnO-AgNPs were homogeneously dispersed in the PVA/Cs matrix and the crystallinity increased with increasing nanosized filler content. Compared with pure PVA/Cs, the tensile strength and modulus in the films increased from 0.055 to 0.205 GPa and from 0.395 to 1.20 GPa, respectively. Ultraviolet and visible light can be efficiently absorbed by incorporating ZnO-AgNPs into a PVA/Cs matrix, suggesting that these bionanocomposite films show good visibility and ultraviolet-shielding effects. The bionanocomposite films had excellent antimicrobial properties, killing both Gram-negative Salmonella choleraesuis and Gram-positive Staphylococcus aureus. The enhanced physical properties achieved by incorporating CNC/ZnO-AgNPs could be beneficial in various applications. PMID:24790433
Azizi, Susan; Ahmad, Mansor Bin; Hussein, Mohd Zobir; Ibrahim, Nor Azowa; Namvar, Farideh
Cellulose Nanocrystals/ZnO as a Bifunctional Reinforcing Nanocomposite for Poly(vinyl alcohol)/Chitosan Blend Films: Fabrication, Characterization and Properties
In this study, cellulose nanocrystals/zinc oxide (CNCs/ZnO) nanocomposites were dispersed as bifunctional nano-sized fillers into poly(vinyl alcohol) (PVA) and chitosan (Cs) blend by a solvent casting method to prepare PVA/Cs/CNCs/ZnO bio-nanocomposites films. The morphology, thermal, mechanical and UV-vis absorption properties, as well antimicrobial effects of the bio-nanocomposite films were investigated. It demonstrated that CNCs/ZnO were compatible with PVA/Cs and dispersed homogeneously in the polymer blend matrix. CNCs/ZnO improved tensile strength and modulus of PVA/Cs significantly. Tensile strength and modulus of bio-nanocomposite films increased from 55.0 to 153.2 MPa and from 395 to 932 MPa, respectively with increasing nano-sized filler amount from 0 to 5.0 wt %. The thermal stability of PVA/Cs was also enhanced at 1.0 wt % CNCs/ZnO loading. UV light can be efficiently absorbed by incorporating ZnO nanoparticles into a PVA/Cs matrix, signifying that these bio-nanocomposite films show good UV-shielding effects. Moreover, the biocomposites films showed antibacterial activity toward the bacterial species Salmonella choleraesuis and Staphylococcus aureus. The improved physical properties obtained by incorporating CNCs/ZnO can be useful in variety uses.
Azizi, Susan; Ahmad, Mansor B.; Ibrahim, Nor Azowa; Hussein, Mohd Zobir; Namvar, Farideh
Cellulose Nanocrystals/ZnO as a Bifunctional Reinforcing Nanocomposite for Poly(vinyl alcohol)/Chitosan Blend Films: Fabrication, Characterization and Properties.
In this study, cellulose nanocrystals/zinc oxide (CNCs/ZnO) nanocomposites were dispersed as bifunctional nano-sized fillers into poly(vinyl alcohol) (PVA) and chitosan (Cs) blend by a solvent casting method to prepare PVA/Cs/CNCs/ZnO bio-nanocomposites films. The morphology, thermal, mechanical and UV-vis absorption properties, as well antimicrobial effects of the bio-nanocomposite films were investigated. It demonstrated that CNCs/ZnO were compatible with PVA/Cs and dispersed homogeneously in the polymer blend matrix. CNCs/ZnO improved tensile strength and modulus of PVA/Cs significantly. Tensile strength and modulus of bio-nanocomposite films increased from 55.0 to 153.2 MPa and from 395 to 932 MPa, respectively with increasing nano-sized filler amount from 0 to 5.0 wt %. The thermal stability of PVA/Cs was also enhanced at 1.0 wt % CNCs/ZnO loading. UV light can be efficiently absorbed by incorporating ZnO nanoparticles into a PVA/Cs matrix, signifying that these bio-nanocomposite films show good UV-shielding effects. Moreover, the biocomposites films showed antibacterial activity toward the bacterial species Salmonella choleraesuis and Staphylococcus aureus. The improved physical properties obtained by incorporating CNCs/ZnO can be useful in variety uses. PMID:24945313
Azizi, Susan; Ahmad, Mansor B; Ibrahim, Nor Azowa; Hussein, Mohd Zobir; Namvar, Farideh
Preparation and properties of poly(vinyl alcohol)/chitosan blend bionanocomposites reinforced with cellulose nanocrystals/ZnO-Ag multifunctional nanosized filler
A series of novel bionanocomposites were cast using different contents of zinc oxide-silver nanoparticles (ZnO-AgNPs) stabilized by cellulose nanocrystals (CNC) as multifunctional nanosized fillers in poly(vinyl alcohol)/chitosan (PVA/Cs) matrices. The morphological structure, mechanical properties, ultraviolet-visible absorption, and antimicrobial properties of the prepared films were investigated as a function of their CNC/ZnO-AgNP content and compared with PVA/chitosan/CNC bionanocomposite films. X-ray diffraction and field emission scanning electron microscopic analyses showed that the CNC/ZnO-AgNPs were homogeneously dispersed in the PVA/Cs matrix and the crystallinity increased with increasing nanosized filler content. Compared with pure PVA/Cs, the tensile strength and modulus in the films increased from 0.055 to 0.205 GPa and from 0.395 to 1.20 GPa, respectively. Ultraviolet and visible light can be efficiently absorbed by incorporating ZnO-AgNPs into a PVA/Cs matrix, suggesting that these bionanocomposite films show good visibility and ultraviolet-shielding effects. The bionanocomposite films had excellent antimicrobial properties, killing both Gram-negative Salmonella choleraesuis and Gram-positive Staphylococcus aureus. The enhanced physical properties achieved by incorporating CNC/ZnO-AgNPs could be beneficial in various applications.
Optimization of industrial CSTR for vinyl acetate polymerization using novel shuffled frog leaping based hybrid algorithms and dynamic modeling
Industrial scale continuous stirred tank reactor (CSTR) for production and grade transitions of poly vinyl acetate (PVAc) at the different reactor sizes was investigated. Such reactor is known to show oscillatory behavior and to have periodic limit points, particularly at high molecular weights. Four efficient novel hybrid optimization methods which use variable population size genetic algorithm (VPGA), bacterial optimization algorithm
Hallas Pakravesh; Akbar Shojaei
Novel silicificated PVAc/POSS composite nanofibrous mat via facile electrospinning technique: potential scaffold for hard tissue engineering.
This study presents the fabrication of novel porous silicificated PVAc/POSS composite nanofibers by facile electrospinning technique and the interaction of synthesized mats with simulated body fluid (SBF). The physicochemical properties of the electrospun composites were determined by scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, electron probe micro-analysis, X-ray diffraction and thermogravimetry analysis. To examine the in vitro cytotoxicity, mouse myoblast C2C12 cells were treated with pristine and composite nanofibrous mats and the viability of cells was analyzed by cell counting kit-8 assay at regular time intervals. Our results indicated the enhanced nucleation and the formation of apatite-like structures at the surface of silicificated PVAc/POSS during the incubation of electrospun mats in SBF solution. Cytotoxicity experiments designated that the myoblasts could attach to the composite after being cultured. We observed in the present study that PVAc/POSS nanofibrous mat could support cell adhesion and guide the spreading behavior of myoblasts. We conclude that the new electrospun silicificated PVAc/POSS composite scaffold with unique porous morphology have excellent biocompatibility. Consequently, our investigation results showed that the as-spun porous PVAc/POSS composite nanofibrous scaffold could be a potential substrate for the proliferation and mineralization of osteoblasts, enhancing bone regeneration. The biocomposite mats represent a promising biomaterial to be exploited for various tissue engineering applications such as guided bone regeneration. PMID:23107958
Ha, Yu-Mi; Amna, Touseef; Kim, Mi-Hee; Kim, Hyun-Chel; Hassan, M Shamshi; Khil, Myung-Seob
Fabrication and characterization of cobalt ferrite (CoFe 2O 4) nanofibers by electrospinning
By sol¢gel process and electrospinning method, cobalt ferrite\\/polyvinyl acetate (PVAc) composite fiber was obtained. Cobalt ferrite (CoFe2O4) nanofibers were synthesized by calcination of the cobalt ferrite\\/polyvinyl acetate (PVAc) composite fiber with several temperatures. The nanofibers were characterized by SEM, FT-IR, XRD and EXAFS. The diameter of nanofibers was slightly decreased with increasing the calcination temperature. The fibers calcined at 800░C
Young-Wan Ju; Jae-Hyun Park; Hong-Ryun Jung; Sung-June Cho; Wan-Jin Lee
Discoloration of Polyvinyl Butyral
NASA Technical Reports Server (NTRS)
Report presents results of study of discoloration in polyvinyl butyral (PVB). Clear PVB gradually turns yellowish brown in simulated-aging tests and outdoor environmental tests. Discoloration severely reduces solar-cell output. Using methods of modern analytical chemistry - transmission absorption, Fourier transform infrared absorption, atomic absorption spectroscopy, and scanning-electron microscopy - study uncovered major cause of yellowing.
Kim, Q.; Shumka, A.
Graft polymerization of vinyl acetate onto starch. Saponification to starch-g-poly(vinyl alcohol). [. gamma. rays
Graft polymerizations of vinyl acetate onto granular cornstarch were initiated by cobalt-60 irradiation of starch-monomer-water mixtures, and ungrafted poly(vinyl acetate) was separated from the graft copolymer by benzene extraction. Conversions of monomer to polymer were quantitative at a radiation dose of 1.0 Mrad. Over half of the polymer was present as ungrafted poly(vinyl acetate) (grafting efficiency less than 50%), and
G. F. Fanta; R. C. Burr; W. M. Doane; C. R. Russell
Heat resistance poly(vinyl alcohol) hydrogel
Six methods were used to evaluate the heat resistance of poly(vinyl alcohol) (PVA) hydrogel prepared by a combination of electron beam irradiation and acetalization of PVA. The physical properties of the hydrogel depended on the degree of acetilization which was affected by content of water in PVA sheet of acetalization in formaldehyde solution at 60░C. It was found that the optimum water content was 20-30%. The acetalized PVA sheet gave maximum tensile strength in electron beams irradiation at 100 kGy. The tensile strength of the hydrogel film increased to 20 MPa from 14 MPa by the irradiation. Heat resistance of the hydrogel was evaluated by measuring the mechanical properties after sterilization in a steam autoclave at 121░C for 90 min. The tensile strength decreased to 10 MPa whereas the elongation at break increased to 300%. The tackiness of the hydrogel was improved by radiation grafting of acrylic acid. Wholesomeness of the hydrogel as a wound dressing was evaluated by attaching to a burn or wound of the back skin of marmots. Advantages of the hydrogel over a gauze dressing were homogeneous adhesion to the affected parts, easy removal without damage to renewed skin and slightly faster rate of reconstruction of the injured skin.
Yoshii, F.; Makuuchi, K.; Darwis, D.; Iriawan, T.; Razzak, M. T.; Rosiak, Janusz M.
Improvement of the synthetic tri-peptide vaccine (S3Pvac) against porcine Taenia solium cysticercosis in search of a more effective, inexpensive and manageable vaccine.
Vaccination of pigs may curtail Taenia solium transmission by reducing the number of cysticerci, the precursors of adult intestinal tapeworms in humans. Several antigen preparations induce protection against porcine cysticercosis in experimental settings but only one subunit vaccine (S3Pvac) has been tested and proved effective in the field against naturally acquired disease. Besides improving of the vaccine's effectiveness, significant reductions in production costs and in the logistics of its administration are necessary for the feasibility of nationwide control programs. This review highlights the development of several versions of S3Pvac aimed to increase effectiveness, reduce costs and increase feasibility by novel delivery systems and alternative routes of administration. PMID:17188784
Sciutto, Edda; Rosas, Gabriela; Hernßndez, Marisela; Morales, Julio; Cruz-Revilla, Carmen; Toledo, Andrea; Manoutcharian, Karen; Gevorkian, Goar; Blancas, Abel; Acero, Gonzalo; Hernßndez, Beatriz; Cervantes, Jacquelynne; Bobes, Raul J; Goldbaum, Fernando A; Huerta, Mirna; Diaz-Orea, Alicia; Fleury, Agnes; de Aluja, Aline S; Cabrera-Ponce, Jose Luis; Herrera-Estrella, Luis; Fragoso, Gladis; Larralde, Carlos
Inexpensive anti-cysticercosis vaccine: S3Pvac expressed in heat inactivated M13 filamentous phage proves effective against naturally acquired Taenia solium porcine cysticercosis.
In search of reducing vaccine production costs', a recombinant M13 phage version of the anti-cysticercosis tripeptide vaccine (S3Pvac) was developed. The efficacy of S3Pvac-Phage vs. placebo was evaluated in a randomized trial that included 1,047 rural pigs in 16 villages of Central Mexico. Three to five months after vaccination 530 pigs were examined by tongue inspection. At 5-27 months of age, 331 pigs (197 vaccinated/134 controls) were inspected at necropsy. Vaccination reduced 70% the frequency of tongue cysticercosis and, based on necropsy, 54% of muscle-cysticercosis and by 87% the number of cysticerci. PMID:18440675
Morales, Julio; MartĒnez, Josķ Juan; Manoutcharian, Karen; Hernßndez, Marisela; Fleury, Agnes; Gevorkian, Goar; Acero, Gonzalo; Blancas, Abel; Toledo, Andrea; Cervantes, Jacquelynne; Maza, Victor; Quet, Fabrice; Bonnabau, Henri; de Aluja, Aline S; Fragoso, Gladis; Larralde, Carlos; Sciutto, Edda
Characterization of poly(vinyl acetate) based floating matrix tablets.
Floating Kollidon SR matrix tablets containing Propranolol HCl were developed and characterized with respect to drug release characteristics and floating strength. Kollidon SR was able to delay Propranolol HCl release efficiently. Drug release kinetics was evaluated using the Korsmeyer-Peppas model and found to be governed by Fickian diffusion. Tablet floating started immediately and continued for 24 h. It was possible to monitor the floating strength of the matrix devices using a simple experimental setup. Floating strength was related to Kollidon SR level with improved floating characteristics for samples with a high polymer/drug ratio. Swelling characteristics of the tablets were analyzed by applying the equation according to Therien-Aubin et al. The influence of the polymer content on swelling characteristics was found to be only marginal. Furthermore, the new method of benchtop MRI was introduced to study the water diffusion and swelling behaviour non-invasively and continuously. PMID:18180069
Str³bing, Sandra; Metz, Hendrik; Mõder, Karsten
Abiraterone acetate.
Abiraterone acetate (CB 7630; CB7630; JNJ-212082), the 3?-acetate prodrug of abiraterone, is structurally related to ketoconazole and is being developed by Cougar Biotechnology as a hormonal therapy for advanced prostate and breast cancers. As a selective inhibitor of adrenal androgens, it is thought to be a safer product than existing second-line hormonal therapies. This review discusses the key development milestones and therapeutic trials of this drug. PMID:21171672
Preparation and properties of poly(vinyl alcohol)¢clay nanocomposite materials
A series of polymer¢clay nanocomposite (PCN) materials that consist of poly(vinyl alcohol) (PVA) and layered montmorillonite (MMT) clay are prepared by effectively dispersing the inorganic nanolayers of MMT clay in organic PVA matrix via an in situ free radical polymerization with AIBN as initiator. Organic vinyl acetate monomers are first intercalated into the interlayer regions of organophilic clay hosts and
Yuan-Hsiang Yu; Ching-Yi Lin; Jui-Ming Yeh; Wei-Hsiang Lin
Synthesis and properties of amphiphilic vinyl acetate triblock copolymers prepared by copper mediated living radical polymerisation
Polymerisation of vinyl acetate by conventional free radical polymerisation using a diazo initiator followed by copper mediated living radical polymerisation with a range of monomers was studied. This method led to the synthesis of triblock copolymers. We have thus successfully prepared several new ABA triblock copolymers where B is poly(vinyl acetate) and A is (dimethylamino)ethyl methacrylate (DMAEMA), (polyethylene glycol) methyl
Delphine Batt-Coutrot; David M. Haddleton; Adam P. Jarvis; Ray L. Kelly
Method for the recycling of polyvinyl butyral
US Patent & Trademark Office Database
Method for the recycling of polyvinyl butyral based on obtaining recycled polyvinyl butyral (PVB) from laminated glass which is shattered and the polyvinyl butyral (PVB) is separated. The sheet obtained is cut into pieces and cleaned to eliminate dirt and foreign matter. The solid state PVB is subjected to a first polyvinyl butyral (PVB) purification stage with a chemical treatment with a first reagent and a final chemical treatment with a second reagent. The obtained purified polyvinyl butyral is suitable to be used in the manufacture of laminated glass.
Polyvinyl formal resin plates impregnated with lipase-entrapped sol¢gel polymer for flavor ester synthesis
Polyvinyl formal (PVF) resin plate was used as a support for forming organic¢inorganic hybrid sol¢gel polymer within its pores. Candida cylindracea lipase immobilized by entrapment in such hybrid sol¢gel polymers made from tetramethoxysilane (TMOS) and propyltrimethoxysilane (PTMS) could efficiently catalyze direct esterification reaction between geraniol and acetic acid in anhydrous hexane for synthesis of the flavor ester geranyl acetate. The
Jyh-Ping Chen; You-Nam Hwang
Polyvinyl Esters of Omega-H-Perfluoroacids and Polyvinyl Alcohol Obtained from Them,
By means of radical polymerization at 20 we obtained polyvinyl esters of omega-H-perfluoroacids from monomers. The product of their saponification - polyvinyl alcohol (PVA) - differs significantly from PVA which is obtained by other methods (mainly with r...
Y. N. Rostovskiy L. D. Budovskaya
Identification Method of Synthetic Polymers by High-Performance Liquid Chromatography
Polyvinyl chloride (PVC), polyvinyl acetate (PVAc), and their copolymers and blends, polystyrene, poly(methyl, ethyl, and butyl) acrylates and methacrylates were dissolved in tetrahydrofu-ran (THF), respectively, and the solutions were injected into a column of silica gel having a pore diameter of 30 A and eluted with the mobile phases of THF, chloroform, ethyl acetate, methanol, methylethylketone, acetonitrile and 1, 2-dichloroethane
Sadao Mori; Sadao
[Preparation and clinical application of polyvinyl alcohol/drug-loaded chitosan microsphere composite wound dressing].
In order to prepare and apply the polyvinyl alcohol/drug-loaded chitosan microspheres composite wound dressing, we first prepared chitosan microspheres by emulsion cross-linking method, and then added chitosan microspheres into the reactants during the acetalization of polyvinyl alcohol and formaldehyde. We further studied the morphology, water absorption, swelling degree, mechanical properties and in vitro release of the sponge with different amount of chitosan microspheres. The results showed that polyvinyl alcohol/drug-loaded chitosan composite sponge has porous structure with connectionism. Increasing the amount of chitosan microspheres would make the apertures smaller, so that the water absorption and the swelling of sponge decreased, but the tensile strength and compressive strength increased. With the increase of the amount of chitosan microspheres, the drug absorption of cefradine and the release rate increase, and the release time become longer. With the results of toxicity grade of 0 to 1, this type of composite sponge is non-toxic and meets the requirement of biocompatibility. The observation of rabbit nasal cavity after surgical operation suggested that polyvinyl acetal sponge modified with the chitosan has antiphlogistic, hemostatic and non-adherent characteristic, and can promote the healing and recovering of the nasalmucosa. After using this composite material, best growing surroundings for patients' granulation tissue were provided. Exposed bone and tendon were covered well with granulation tissue. PMID:21604506
Zhang, Xiuju; Lin, Zhidan; Chen, Wenbin; Song, Ying; Li, Zhizhong
Poly(vinyl alcohol) hydrogel fixation on poly(ethylene terephthalate) surface for biomedical application
A surface modification technique was developed for the covalent immobilization of poly(vinyl alcohol) (PVA) hydrogel onto poly(ethylene terephthalate) (PET) to improve the biocompatibility of the film. The PET film was first graft copolymerized with poly(ethylene glycol) monomethacrylate (PEGMA) in the presence of ethylene glycol dimethacrylate (EGDMA) as crosslinker, and then oxidized with a mixture of acetic anhydride (Ac2O) and dimethyl
Yali Li; K. G. Neoh; E. T. Kang
Preparation of polymer decorated graphene oxide by ?-ray induced graft polymerization
Herein, we report a facile approach to decorate graphene oxide (GO) sheets with poly(vinyl acetate) (PVAc) by ?-ray irradiation-induced graft polymerization. The content of PVAc in the obtained sample, i.e., PVAc grafted GO (GO-g-PVAc) is calculated by the loss weight in thermogravimetric analysis (TGA) curves. A GO-g-PVAc sample with a degree of grafting (DG) of 28.5% was well dispersed in common organic solvents and the dispersions obtained were extremely stable at room temperature without any aggregation, even after standing for 2 months. The excellent dispersibility and stability of GO-g-PVAc in common organic solvents are readily rationalized in terms of the full coverage of PVAc chains and solvated layer formation on graphene oxide sheets surface, which weakens the interlaminar attraction of GO sheets. This approach presents a facile route for the preparation of dispersible GO and shows great potential in the preparation of graphene-based composites by solution-processes.Herein, we report a facile approach to decorate graphene oxide (GO) sheets with poly(vinyl acetate) (PVAc) by ?-ray irradiation-induced graft polymerization. The content of PVAc in the obtained sample, i.e., PVAc grafted GO (GO-g-PVAc) is calculated by the loss weight in thermogravimetric analysis (TGA) curves. A GO-g-PVAc sample with a degree of grafting (DG) of 28.5% was well dispersed in common organic solvents and the dispersions obtained were extremely stable at room temperature without any aggregation, even after standing for 2 months. The excellent dispersibility and stability of GO-g-PVAc in common organic solvents are readily rationalized in terms of the full coverage of PVAc chains and solvated layer formation on graphene oxide sheets surface, which weakens the interlaminar attraction of GO sheets. This approach presents a facile route for the preparation of dispersible GO and shows great potential in the preparation of graphene-based composites by solution-processes. Electronic Supplementary Information (ESI) available: XPS and photos. See DOI: 10.1039/c2nr11724j
Zhang, Bowu; Zhang, Yujie; Peng, Cheng; Yu, Ming; Li, Linfan; Deng, Bo; Hu, Pengfei; Fan, Chunhai; Li, Jingye; Huang, Qing
Polyvinyl alcohol hydrogels for iontohporesis
Transdermal therapeutic systems propound controlled release of active ingredients through the skin into the systemic circulation in a predictive manner. Drugs administered through these systems escape first-pass metabolism and maintain a steady state scenario similar to a continuous intravenous infusion for up to several days. The iontophoresis deal with the systemic delivery of the bioactive agents (drug) by applying an electric current. It is basically an injection without the needle. The iontophoretic system requires a gel-based matrix to accommodate the bioactive agent. Hydrogels have been used by many investigators in controlled-release drug delivery systems because of their good tissue compatibility and easy manipulation of swelling level and, thereby, solute permeability. In this work we have prepared polyvinyl alcohol (PVA) hydrogel. We have cross linked polyvinyl alcohol chemically with Glutaraldehyde with different wt%. FTIR study reveals the chemical changes during cross linking. Swelling in water, is done to have an idea about drug loading and drug release from the membrane. After drug loading to the hydrogels, we have studied the drug release property of the hydrogels using salicylic acid as a model drug.
Bera, Prasanta; Alam, Asif Ali; Arora, Neha; Tibarewala, Dewaki Nandan; Basak, Piyali
Hydrolysis of ethyl acetate:a pervaporation study
The influence of temperature on the separation factor, diffusion process, permeation rate, and permeability coefficient (k) for hydrolysis of ethyl acetate using a standard poly(vinyl alcohol) (PVA) membrane by pervaporation was investigated. The preliminary data presented in this work was obtained using a simple pervaporation technique built in-house. The experiments were conducted at 80, 65, 50 and 35░C. The initial
Habib I. Shaban
Fluorescence lifetime distributions: Applications to high and low viscosity media in polymer blend-like particles
Fluorescence measurements were carried out in poly(vinyl acetate) (PVAc) particles which were prepared by dispersion polymerization in isooctane using a copolymer of 2-ethylhexyl methacrylate (PEHMA) as a steric stabilizer. These reactive particles were labelled by naphthalene (N) in the stabilizer phase. N fluorescence decay profiles were measured and apparent dimension of dapp = 2.3 for the energy transfer process was
ų. Pekcan
Further evaluation of the synthetic peptide vaccine S3Pvac against Taenia solium cysticercosis in pigs in an endemic town of Mexico.
Taenia solium cysticercosis is a parasitic disease frequently affecting human health and the pig industry in many developing countries. A synthetic peptide vaccine (designated S3Pvac) against porcine cysticercosis has been developed previously as an aid to interrupt transmission and has been shown to be effective. The results of the present study support the effectiveness of the vaccine under endemic field conditions. However, given the time-frame of the vaccination trial, no changes in the local levels of transmission were detectable before and after vaccination using sentinel pigs. Thus, this investigation shows the limited usefulness of single vaccination as the sole means of interrupting Taenia solium transmission in an endemic region. PMID:16948875
Sciutto, E; Morales, J; MartĒnez, J J; Toledo, A; Villalobos, M N; Cruz-Revilla, C; Meneses, G; Hernßndez, M; DĒaz, A; Rodarte, L F; Acero, G; Gevorkian, G; Manoutcharian, K; Paniagua, J; Fragoso, G; Fleury, A; Larralde, R; De Aluja, A S; Larralde, C
Irradiation of polyvinyl alcohol and polyvinyl pyrrolidone blended hydrogel for wound dressing
Polyvinyl alcohol and polyvinyl pyrrolidone (PVA¢PVP) blended hydrogel for wound dressing has been prepared by using gamma rays irradiation technique. The gel fraction, mechanical properties, the water content and water absorption performance of the hydrogels were measured. It was found that the gel fraction increases with increasing irradiation dose but never reaches 100% of gel. The PVA\\/PVP blended hydrogel has
Mirzan T Razzak; Darmawan Darwis; Zainuddin; Sukirno
A review of polyvinyl alcohol and its uses in cartilage and orthopedic applications.
Polyvinyl alcohol (PVA) is a synthetic polymer derived from polyvinyl acetate through partial or full hydroxylation. PVA is commonly used in medical devices due to its low protein adsorption characteristics, biocompatibility, high water solubility, and chemical resistance. Some of the most common medical uses of PVA are in soft contact lenses, eye drops, embolization particles, tissue adhesion barriers, and as artificial cartilage and meniscus. The purpose of this review is to evaluate the available published information on PVA with respect to its safety as a medical device implant material for cartilage replacement. The review includes historical clinical use of PVA in orthopedics, and in vitro and in vivo biocompatibility studies. Finally, the safety recommendation involving the further development of PVA cryogels for cartilage replacement is addressed. PMID:22514196
Baker, Maribel I; Walsh, Steven P; Schwartz, Zvi; Boyan, Barbara D
Influence of interfacial properties of styrene\\/butadiene latex on the interaction with poly(vinyl alcohol) in aqueous media
The interfacial properties of styrene\\/butadiene latex were found to play a substantial role in its interaction with partially hydrolysed polyvinyl acetate (PVOH\\/Ac) in aqueous solutions. In particular, the level of carboxylation of the latex particles governs the adsorption process. A slightly hydrophobic PVOH\\/Ac is weakly adsorbed onto medium carboxylated latex at low equilibrium concentrations, whereas a multilayer adsorption occurs at
Kaj Backfolk; Serge Lagerge; Jarl B. Rosenholm; Dan Eklund
Effect of Renal Embolization with Trisacryl and PAVc
OBJECTIVES Evaluate the degree of vascular occlusion, vascular recanalization, and necrosis of the vascular wall caused by polyvinyl alcohol-covered polyvinyl acetate (PVAc) particles compared to trisacryl particles after renal embolization. METHODS Seventy-nine female albino New Zealand rabbits underwent arterial catheterization of the right kidney. Thirty-three animals were embolized with trisacryl particles, thirty-one with PVAc particles, and fifteen were kept as controls. Four animals were excluded (three trisacryl and one PVAc) due to early death. Five subgroups of six animals were created. The animals in the different groups were sacrificed either 48 hours, 5 days, 10 days, 30 days, or 90 days after embolization. The control group was divided into subgroups of three animals each and kept for the same periods of time. The kidneys were dyed with hematoxylin-eosin and MassonÆs trichrome and then examined using optical microscopy. RESULTS There were significant differences in the degree of vascular occlusion caused by the trisacryl and the PVAc particles between the five-day and the ten-day groups. Additional differences were noted between the five-day and 48-hour groups in regard to the amount of necrosis. For both findings, the PVAc group members showed adequate tissue reaction (ischemia and volumetric reduction) and less recanalization than those treated with trisacryl. CONCLUSION The use of PVAc as an embolization material exhibited an adequate tissue reaction (ischemia and volumetric reduction), more expressive vascular occlusion and necrosis, and less recanalization than the trisacryl material.
de Assis Barbosa, Leandro; Caldas, Jose Guilherme Mendes Pereira; Conti, Mario Luiz; Malheiros, Denise Maria Avancini Costa; Ramos, Francisco Ferreira
Pallidol hexa-acetate ethyl acetate monosolvate
The entire molŁecule of pallidol hexaŁacetate {systematic name: (▒)-(4bR,5R,9bR,10R)-5,10-bisŁ[4-(acetŁyloxy)phenŁyl]-4b,5,9b,10-tetraŁhydroŁindenoŁ[2,1-a]indene-1,3,6,8-tetrayl tetraŁacetate} is completed by the application of twofold rotational symmetry in the title ethyl acetate solvate, C40H34O12ĘC4H8O2. The ethyl acetate molŁecule was highly disordered and was treated with the SQUEEZE routine [Spek (2009 ?). Acta Cryst. D65, 148¢155]; the crystallographic data take into account the presence of the solvent. In pallidol hexaŁacetate, the dihedral angle between the fused five-membered rings (r.m.s. deviation = 0.100?┼) is 54.73?(6)░, indicating a significant fold in the molŁecule. Significant twists between residues are also evident as seen in the dihedral angle of 80.70?(5)░ between the five-membered ring and the pendent benzene ring to which it is attached. Similarly, the acetate residues are twisted with respect to the benzene ring to which they are attached [CŚO(carbŁoxy)ŚCŚC torsion angles = ?70.24?(14), ?114.43?(10) and ?72.54?(13)░]. In the crystal, a three-dimensional architecture is sustained by CŚH?O interŁactions which encompass channels in which the disordered ethyl acetate molŁecules reside.
Mao, Qinyong; Taylor, Dennis K.; Ng, Seik Weng; Tiekink, Edward R. T.
21 CFR 175.270 - Poly(vinyl fluoride) resins.
Code of Federal Regulations, 2010 CFR
...2009-04-01 true Poly(vinyl fluoride) resins. 175.270 Section 175.270 Food and Drugs...Coatings ¦ 175.270 Poly(vinyl fluoride) resins. Poly(vinyl fluoride) resins identified in this section may be safely...
Code of Federal Regulations, 2012 CFR
...2012-04-01 false Poly(vinyl fluoride) resins. 175.270 Section 175.270 Food and Drugs...Coatings ¦ 175.270 Poly(vinyl fluoride) resins. Poly(vinyl fluoride) resins identified in this section may be safely...
Code of Federal Regulations, 2011 CFR
...2011-04-01 false Poly(vinyl fluoride) resins. 175.270 Section 175.270 Food and Drugs...Coatings ¦ 175.270 Poly(vinyl fluoride) resins. Poly(vinyl fluoride) resins identified in this section may be safely...
Polyfunctional Biologically Active Polyvinyl Alcohol Film Materials
Incorporation of sodium alginate in the spinning solution in the amount of 2% decreases the rate of inactivation of protease C immobilized in the structure of a polyvinyl alcohol film material by two times and decreases the amount of desorbed polyhexamethyleneguanidine hydrochloride by ten times, giving the film self-disinfecting properties. Addition of sodium tetraborate in the spinning solution increases the
T. N. Yudanova; I. F. Skokova; E. Yu. Aleshina; L. S. Gal'braikh
Construction of Experimental Polyvinyl Chloride (PVC) Roofing.
Polyvinyl chloride (PVC) singly-ply roofing systems have been installed at three U.S. military facilities for long-term evaluation (10 years) in three environments. Commercial PVC systems previously had been shown to offer an alternative to conventional b...
M. J. Rosenfield
Synthesis of micro-size magnetic polymer adsorbent and its application for the removal of Cu(II) ion
This study is aimed at the synthesis of micro-size magnetic polymer adsorbent (MPA) coupling with metal chelating ligands of iminodiacetic acid (IDA) and its application for the removal of Cu(II) ion. Firstly, the super-paramagnetic Fe3O4 called magnetite was prepared via the chemical co-precipitation method. The magnetite was then coated with polyvinyl acetate (PVAC) via the suspension polymerization with vinyl acetate
Jyi-Yeong Tseng; Ching-Yuan Chang; Yi-Hung Chen; Chiung-Fen Chang; Pen-Chi Chiang
Influence of solvent and polymer sort on anomalous rheological behavior of polymer solution at high dilution
The rheological behavior of polyvinyl acetate (PVAc) in N,N?=dimethylformamide (DMF), methyl ethyl ketone (MEK), 1,2-dichloroethane\\u000a (DCE), tetrahydrofuran (THF) and toluene (TOL), polystyrene (PS) in DMF, MEK, DCE, THF and cyclohexane (CYH), and random ethylene-vinyl\\u000a acetate (EVA) copolymer in DCE, TOL, CYH with and without surfactant of Span80 and in the DCE\\/CYH solvent mixtures with surfactant\\u000a of Span80 was examined at
Qian Jin-wen; Zhou Guo-hai; Zheng Qiang; Wu Ping-dong
Catalytic poly(vinyl alcohol) functionalized membranes obtained by gamma irradiation
Polymeric catalytic membranes bearing sulfonic acid functions have been prepared by mutual gamma irradiation at a 60Co source, of poly(vinyl alcohol) (PVA) membranes and methanesulfonic acid. The effect of various synthesis conditions on membranes' physical-chemical properties and catalytic activity in the esterification reaction between acetic acid and isoamyl alcohol to obtain isoamyl acetate (banana flavor), was evaluated. The membranes were characterized by ATR-FTIR, TPP, AFM and SEM. Water contact angle determinations were also performed. The obtained results showed that within the range of conditions studied the increase in sulfonic acid groups' content is accompanied by an enhancement in the membranes catalytic activity, while the increase in absorbed dose leads to a decrease in catalytic activity.
Casimiro, M. H.; Silva, A. G.; Pinto, J. V.; Ramos, A. M.; Vital, J.; Ferreira, L. M.
Preparation of vinyl acetate
This invention pertains to the preparation of vinyl acetate by contacting a mixture of hydrogen and ketene with a heterogeneous catalyst containing a transition metal to produce acetaldehyde, which is then reacted with ketene in the presence of an acid catalyst to produce vinyl acetate.
Tustin, Gerald Charles (Kingsport, TN); Zoeller, Joseph Robert (Kingsport, TN); Depew, Leslie Sharon (Kingsport, TN)
Tustin, G.C.; Zoeller, J.R.; Depew, L.S.
Immunological evaluation of mannosylated chitosan nanoparticles based foot and mouth disease virus DNA vaccine, pVAC FMDV VP1-OmpA in guinea pigs.
A DNA vaccine for foot and mouth disease (FMD) based on mannosylated chitosan nanoparticles was evaluated in guinea pigs. The DNA construct was comprised of FMD virus full length-VP1 gene and outer membrane protein A (Omp A) gene of Salmonella typhimurium as a Toll-like receptor (TLR)-ligand in pVAC vector. Groups of guinea pigs immunized either intramuscularly or intra-nasally were evaluated for induction of virus neutralizing antibodies, Th1(IgG2) and Th2 (IgG1) responses, lymphocyte proliferation, reactive nitrogen intermediate production, secretory IgA for naso-mucosal immune response and protection upon homotypic type O virulent FMD virus challenge. The results indicate the synergistic effect of OmpA on the immunogenic potential of FMD DNA vaccine construct delivered using mannosylated chitosan nano-particles by different routes of administration. These observations suggest the substantial improvement in all the immunological parameters with enhanced protection in guinea pigs. PMID:24656961
Nanda, Raj Kishore; Hajam, Irshad Ahmed; Edao, Bedaso Mammo; Ramya, Kalaivanan; Rajangam, Mageswary; Chandra Sekar, Shanmugam; Ganesh, Kondabattula; Bhanuprakash, Veerakyathappa; Kishore, Subodh
Anion receptor-coated separator for lithium-ion polymer battery
Anion receptor-coated separators were prepared by coating poly(ethylene glycol) borate ester (PEGB) as an anion receptor and\\u000a poly(vinyl acetate) (PVAc) as a good adhesive material towards electrodes onto microporous polyethylene (PE) separators. Gel\\u000a polymer electrolytes were fabricated by soaking them in an liquid electrolyte, 1ĀM LiPF6 in EC\\/DEC\\/PC (30\\/65\\/5, wt.%). As the weight ratio of PEGB to PVAc in a
Je An Lee; Jun Young Lee; Myung Hyun Ryou; Gi-Beom Han; Je-Nam Lee; Dong-Jin Lee; Jung-Ki Park; Yong Min Lee
Effect of Heat Treatment on Some Mechanical Properties of Laminated Window Profiles Manufactured Using Two Types of Adhesives
The mechanical properties of laminated window profiles manufactured using two types of adhesives were determined. The objective of this study is to evaluate the effects of heat treatment on some mechanical properties of laminated window profiles that manufactured from Kosipo (Entandrophragma candollei Harms.) using differenet type adhesives. Commercially produced polyurethane based Macroplast UR 7221 and polyvinyl acetate (PVAc) adhesive were used for experiments. The overall test results were found to be comparable to those obtained in the previous studies. Both types of adhesives resulted in significant differences in their strength characteristics at 95% confidence level. Adhesive UR 7221 improved the overall properties of the samples in contrast to PVAc.
Korkut, Derya Sevim; Korkutand, Suleyman; Dilik, Tuncer
Nanofabrication in cellulose acetate.
We have demonstrated nanofabrication with commercialized cellulose acetate. Cellulose acetate is used for bulk nanofabrication and surface nanofabrication. In bulk nanofabrication, cellulose acetate reacts with an e-beam and permanent patterns are formed in it instead of being transferred to other substrates. We have studied the nano relief modulation performance of cellulose acetate before and after development. The depth of the nanopatterns is magnified after development, and is varied by exposing dosage and line width of the pattern. The thinnest 65 nm wide line is achieved in the bulk fabrication. We also demonstrate a binary phase Fresnel lens array which is directly patterned in a cellulose acetate sheet. Because of its unique mechanical and optical properties, cellulose is a good candidate for a template material for soft imprinting lithography. In the surface nanofabrication, cellulose acetate thin film spin-coated on silicon wafers is employed as a new resist for e-beam lithography. We achieved 50 nm lines with 100 nm pitches, dots 50 nm in diameter, and single lines with the smallest width of 20 nm. As a new resist of e-beam lithography, cellulose acetate has high resolution comparable with conventional resists, while having several advantages such as low cost, long stock time and less harmfulness to human health. PMID:19224020
Zeng, Hongjun; Lajos, Robert; Metlushko, Vitali; Elzy, Ed; An, Se Young; Sautner, Joshua
Biochemistry of microbial polyvinyl alcohol degradation
Effect of minor chemical structures such as 1,2-diol content, ethylene content, tacticity, a degree of polymerization, and\\u000a a degree of saponification of the main chain on biodegradability of polyvinyl alcohol (PVA) is summarized. Most PVA-degraders\\u000a are Gram-negative bacteria belonging to the Pseudomonads and Sphingomonads, but Gram-positive bacteria also have PVA-degrading\\u000a abilities. Several examples show symbiotic degradation of PVA by different
Fusako Kawai; Xiaoping Hu
Destruction of polyvinyl chloride under extrusion
An common industrial application of polyvinyl chloride (PVC) is the extrusive insulation of electric wires and cables. Experimental results are presented on the thermal and mechanical destruction of PVC under extrusion. Under extrusion conditions (at temperatures higher than 150 C), the evolution of hydrogen chloride determines practically the entire process of PVC destruction. The use of the present data to establish hygienic standards regarding safe concentrations of PVC destruction products in the work environment is discussed.
Dmitriev, M. T.; Serebriakova, R. V.; Serebriakov, V. N.; Zimin, P. N.; Nastenko, A. V.; Derevianchenko, L. G.; Antsifirova, N. P.; Visloukh, V. V.
Preparation of novel carbon microfiber/carbon nanofiber-dispersed polyvinyl alcohol-based nanocomposite material for lithium-ion electrolyte battery separator.
A novel nanocomposite polyvinyl alcohol precursor-based material dispersed with the web of carbon microfibers and carbon nanofibers is developed as lithium (Li)-ion electrolyte battery separator. The primary synthesis steps of the separator material consist of esterification of polyvinyl acetate to produce polyvinyl alcohol gel, ball-milling of the surfactant dispersed carbon micro-nanofibers, mixing of the milled micron size (~500 nm) fibers to the reactant mixture at the incipience of the polyvinyl alcohol gel formation, and the mixing of hydrophobic reagents along with polyethylene glycol as a plasticizer, to produce a thin film of ~25 ?m. The produced film, uniformly dispersed with carbon micro-nanofibers, has dramatically improved performance as a battery separator, with the ion conductivity of the electrolytes (LiPF6) saturated film measured as 0.119 S-cm(-1), approximately two orders of magnitude higher than that of polyvinyl alcohol. The other primary characteristics of the produced film, such as tensile strength, contact angle, and thermal stability, are also found to be superior to the materials made of other precursors, including polypropylene and polyethylene, discussed in the literature. The method of producing the films in this study is novel, simple, environmentally benign, and economically viable. PMID:23827627
Sharma, Ajit K; Khare, Prateek; Singh, Jayant K; Verma, Nishith
40 CFR 61.64 - Emission standard for polyvinyl chloride plants.
Code of Federal Regulations, 2013 CFR
... Emission standard for polyvinyl chloride plants. 61.64 Section 61.64 Protection... Emission standard for polyvinyl chloride plants. An owner or operator of a polyvinyl chloride plant shall comply with the requirements of...
40 CFR 61.65 - Emission standard for ethylene dichloride, vinyl chloride and polyvinyl chloride plants.
...dichloride, vinyl chloride and polyvinyl chloride plants. 61.65 Section...dichloride, vinyl chloride and polyvinyl chloride plants. An owner or operator...vinyl chloride, and/or polyvinyl chloride plant shall comply with...
The development and characterization of degradable poly(vinyl ester) and poly(vinyl ester)/PEO block copolymers
The development of biodegradable materials is a challenging and important problem in polymer science. A review of the state of the art in degradable materials is presented, which reveals that current biodegradable materials do not exhibit the thermal or mechanical properties necessary for widespread applications. One strategy for toughening polymeric materials, which has previously been applied to non-degradable thermoplastics and thermoplastic elastomers, is the formation of block copolymers. Poly(vinyl esters) (PVE) homopolymers are known to have a wide range of properties, but PVE block copolymers comprise a class of inexpensive and (bio)degradable materials that were previously unknown. Therefore, the synthesis and properties of these block copolymers were explored in an effort to develop robust degradable materials. This thesis research probes the reaction conditions necessary for the reversible-addition fragmentation chain transfer (RAFT) polymerization and chain extension reactions of vinyl ester monomers. PVE di- and triblock copolymers are synthesized and studied, and the triblock copolymers display extremely poor toughness due to their relatively low molecular weights in light of the high entanglement molecular weight of the poly(vinyl acetate) center block. Attempts to improve the mechanical properties of these materials focus on the incorporation of poly(ethylene oxide) (PEO) as a low entanglement molecular weight and biocompatible center block in PVE-containing triblock copolymers. Depending on the choice of PVE endblocks and the overall polymer composition, crystallization of the PEO block can be controlled, confined, or inhibited. Polymers in which PEO crystallization is completely inhibited exhibit enhanced mechanical properties and behave as weak thermoplastics. In order to understand the relationship between the inhibition of PEO crystallization and the mechanical properties of PVE/PEO materials, these polymers were studied using dynamic mechanical spectroscopy, wide angle X-ray scattering, small angle X-ray scattering, differential scanning calorimetry, and uniaxial tensile tests. By combining insights gained from these techniques, a complex picture emerges that explains the enhanced mechanical properties of these materials based on the type and location of thermal transitions, amorphous PEO entanglements, and the strain-induced crystallization of PEO. This work represents an important step toward developing robust materials with tunable properties containing (bio)degradable components.
Lipscomb, Corinne Elizabeth
Mechanisms of acetate formation and acetate activation in halophilic archaea
The halophilic archaea Halococcus (Hc.) saccharolyticus, Haloferax (Hf.) volcanii, and Halorubrum (Hr.) saccharovorum were found to generate acetate during growth on glucose and to utilize acetate as a growth substrate. The mechanisms of acetate formation from acetyl-CoA and of acetate activation to acetyl-CoA were studied. Hc. saccharolyticus, exponentially growing on complex medium with glucose, formed acetate and contained ADP-forming acetyl-CoA
Christopher Brõsen; Peter Sch÷nheit
Impacts of impregnation chemicals on combustion properties of the laminated wood materials produced combination of beech and poplar veneers
The aim of this study was to investigate the effects of impregnation with boron compounds Borax (BX), Boric acid (BA), BX+BA, Imersol-Aqua (IAQUA) and Timbercare-Aqua (TAQUA) on combustion properties of the laminated wood materials produced combination of Oriental beech and poplar veneers bonded with Desmodur-VTKA (DV) and Poly(vinyl acetate) (PVAc) adhesives. The test samples, prepared from beech (Fagus orientalis Lipsky)
Hakan Keskin; Musa Atar; Mahmut Izciler
Impacts of impregnation with boron compounds on the bonding strength of wood materials
The objective of this research was to evaluate bonding strength of poly(vinyl acetate) (PVAc), polyurethane based Desmodur-VTKA (D-VTKA), phenol¢formaldehyde (PF) and melamine¢formaldehyde (MF) adhesives to impregnated wood materials. For this purpose, oriental beech (Fagus orientalis lipsky), white oak (Quercus petraea spp.), Uludag fir (Abies bornm³lleriana Mattf.) and poplar (Populus nigra) woods were impregnated with borax (Bo), boric acid (Ba), Bo+Ba
Ayhan ųzńifńi
Properties of laminated veneer lumber (LVL) made with low density hardwood species: effect of the pressure duration
Cross-linked polyvinyl acetate (PVAc) adhesive and thin veneers of three low density wood species,\\u000a namely silver maple, yellow poplar and aspen, were used to produce LVL engineered wood products using different\\u000a press durations. Density, water absorption, thickness swelling, flexural strength and surface hardness\\u000a were evaluated. Internal bond strength, tensile shear and block shear strengths were tested in dry, accelerated\\u000a (boiling
S. R. Shukla; D. Pascal Kamdem
Polyvinyl alcohol and polyvinyl pyrrolidone (PVA-PVP) blended hydrogel for wound dressing has been prepared by using gamma rays irradiation technique. The gel fraction, mechanical properties, the water content and water absorption performance of the hydrogels were measured. It was found that the gel fraction increases with increasing irradiation dose but never reaches 100% of gel. The PVA/PVP blended hydrogel has a water content in the range between 60% and 80% and water absorption between 40% and 250%. The water vapor transmission rate value (WVTR) of the PVA/PVP blended hydrogel varies between 50 and 200 g/m 2/h. The hydrogel could be considered as good barrier against microbes. According to in vitro assessment it was found that the PVA/PVP blended hydrogel was very useful material that can meet the efficacy requirement and its healing rate was comparable with sterilized gauze and sofratulle.
Razzak, Mirzan T.; Darwis, Darmawan; Zainuddin; Sukirno
Radiation sterilization of hydrocortisone acetate.
The feasibility of using high energy ionizing radiation for the sterilization of hydrocortisone acetate was investigated. Hydrocortisone acetate in the form of powder was exposed to different dose levels of gamma radiation using a Cobalt-60 source. The ir...
A. Charef A. Boussaha
Preparation of porous super-hydrophobic and super-oleophilic polyvinyl chloride surface with corrosion resistance property
Porous super-hydrophobic polyvinyl chloride (PVC) surfaces were obtained via a facile solvent/non-solvent coating process without introducing compounds with low surface energy. The microstructure, wetting behavior, and corrosion resistance of resultant super-hydrophobic PVC coatings were investigated in relation to the effects of dosage of glacial acetic acid and the temperature of drying the mixed PVC solution spread over glass slide substrate. As-prepared PVC coatings had porous microstructure, and the one obtained at a glacial acetic acid to tetrahydrofuran volume ratio of 2.5:10.0 and under a drying temperature of 17 ░C had a water contact angle of 150 ▒ 1.5░, showing super-hydrophobicity. In the meantime, it possessed very small contact angles for liquid paraffin and diiodomethane and good corrosion resistance against acid and alkali corrosive mediums, showing promising applications in self-cleaning, waterproof for outer wall of building, seawater resistant coating, and efficient separation of oil and water.
Kang, Yingke; Wang, Jinyan; Yang, Guangbin; Xiong, Xiujuan; Chen, Xinhua; Yu, Laigui; Zhang, Pingyu
Acetate Production by Methanogenic Bacteria
Methanosarcina barkeri MS and 227 and Methanosarcina mazei S-6 produced acetate when grown on H2-CO2, methanol, or trimethylamine. Marked differences in acetate production by the two bacterial species were found, even though methane and cell yields were nearly the same. M. barkeri produced 30 to 75 ?mol of acetate per mmol of CH4 formed, but M. mazei produced only 8 to 9 ?mol of acetate per mmol of CH4.
Westermann, Peter; Ahring, Birgitte K.; Mah, Robert A.
[Survey of plasticizers in polyvinyl chloride toys].
Plasticizers in 101 samples of polyvinyl chloride (PVC) toys on the Japanese market were surveyed. No phthalates were detected in designated toys, though bis(2-ethylhexyl)phthalate, diisononyl phthalate, diisobutyl phthalate, dibutyl phthalate, diisodecyl phthalate and benzyl butyl phthalate were detected in more than half of other toys. 2,2,4-Tributyl-1,3-pentanediol diisobutylate, o-acetyl tributyl citrate, adipates and diacetyl lauroyl glycerol, which are alternative plasticizers to phthalates, were detected. The results of structural analysis confirmed the presence of di(2-ethylhexyl)terephthalate, tributyl citrate, diisononyl 1,2-cyclohexanedicarboxylate and neopentyl glycol esters; these have not previonsly been reported in Japan. There appears to be a shift in plasticizers used for designated toys from phthalates to new plasticizers, and the number of different plasticizers is increasing. PMID:22450665
Abe, Yutaka; Yamaguchi, Miku; Mutsuga, Motoh; Hirahara, Yoshichika; Kawamura, Yoko
Orientation of cellulose nanowhiskers in polyvinyl alcohol
The goal of this study was to align cellulose nanowhiskers in a polymer using a strong magnetic field and thereby obtain a unidirectional reinforced nanocomposite. Cellulose whiskers (2 wt. %) were incorporated in a polyvinyl alcohol matrix using solution casting with water as the solvent. The suspension was cast and the water was evaporated while a homogeneous magnetic field of 7 T was applied. Different microscopy investigations of prepared nanocomposites indicated that the cellulose whiskers were oriented perpendicular to the direction of the magnetic field. Dynamic mechanical thermal analysis further strengthened the idea of alignment because the results showed that the dynamic modulus of the nanocomposite was around 2 GPa higher at room temperature in the aligned direction compared to the transverse direction.
Kvien, I.; Oksman, K.
Cryotropic gelation of poly(vinyl alcohol) solutions
The mechanisms of the cryotropic gelation of poly(vinyl alcohol) solutions as well as the influence of the characteristics of the polymer and the conditions of the cryogenic treatment on the structure and physicochemical properties of the cryogels obtained are examined. Data on the characteristics of the freezing of concentrated poly(vinyl alcohol) solutions are presented. The influence of soluble additives, possessing different lyotropic properties, on the course of gelation in frozen systems is discussed. The possibility of the cryocracking of poly(vinyl alcohol) chains is considered. The bibliography includes 349 references.
Lozinsky, Vladimir I.
Levulinyl cellulose esters have been produced as an effective renewable binder for architectural coatings. The title compound, C7H10O4 (systematic name: 2-methyl-5-oxoŁtetraŁhydroŁfuran-2-yl acetate), assigned as the esterifying species, was isolated and crystallized to confirm the structure. In the crystal, the molŁecules pack in layers parallel to (102) utilizing weak CŚH?O interŁactions.
Tristram, Cameron; Gainsford, Graeme J.; Hinkley, Simon
Plasma acetate turnover and oxidation.
Plasma acetate turnover and oxidation were determined in 11 healthy subjects by the constant infusion of a trace amount of [1-14C]acetate for 6 h. The subjects ages ranged from 22 to 57 yr. There was a positive correlation (P less than 0.001) between plasma acetate concentration and turnover rate, and a negative correlation (P less than 0.001) between turnover and age. The plasma acetate concentration in the subjects 22--28 yr old was 0.17 vs. 0.13 mM (P less than 0.02) in subjects 40--57 yr old. The plasma acetate turnover rate was also greater in the younger age group (8.23 +/- 0.66 vs. 4.98 +/- 0.64 mumol/min . kg, P less than 0.01). Approximately 90% of the plasma acetate turnover was immediately oxidized to CO2 in both age groups, however, 13.2 +/- 0.89% of the CO2 output in the younger group was derived from plasma acetate oxidation compared to 7.9 +/- 0.94% in the older group (P less than 0.01). The mean plasma acetate concentration, turnover, and oxidation in six cancer patients 47--63 yr old were similar to the values observed in the age-matched healthy subjects. Uptake or output of acetate by various tissues was measured by arterial-venous plasma acetate concentration differences. In seven of eight subjects undergoing elective surgery, the arterial-portal venous concentration difference was negative, which indicated that the gastrointestinal tract can contribute to plasma acetate production. Uptake of plasma acetate by both the leg and liver appeared to be dictated by the arterial acetate concentration. Net production of acetate by both the leg and liver was most often observed at arterial plasma acetate concentrations less than 0.08 mM.
Skutches, C L; Holroyde, C P; Myers, R N; Paul, P; Reichard, G A
Formalized Poly(Vinyl Alcohol) Membranes for Reverse Osmosis.
The permeation properties of formalized poly(vinyl alcohol) membranes are described. The interest of this work is centered on the properties relevant to desalination by reverse osmosis. These membranes, when properly prepared, showed reasonably high water...
A. V. Tobolsky C. T. Chen M. C. Chen Y. J. Chang
21 CFR 177.1670 - Polyvinyl alcohol film.
...HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated...alcohol film is produced from polyvinyl alcohol having a minimum viscosity of 4 centipoises when a 4-percent aqueous solution is...
Wastewater Treatment Facilities for a Polyvinyl Chloride Production Plant.
The report discusses the investigations of various types of wastewater treatment systems to adequately treat wastes from a polyvinyl chloride plant. Both primary and secondary treatment methods were investigated. Waste equalization; solids removal by chem...
Synthesis of boron carbide powder from polyvinyl borate precursor
Polyvinyl borate (PVBO) was prepared by the condensation of poly(vinyl alcohol) (PVA) and boric acid, and used as a precursor for boron carbide. Boron carbide powder was synthesized by the pyrolysis of the PVBO precursor in air at 600Ā░C for 2Āh, followed by heat treatment in Ar flow at 1300Ā░C for 5Āh, which is a relatively low temperature compared with
Ikuo Yanase; Riichi Ogawara; Hidehiko Kobayashi
Investigation on isobaric vapor liquid equilibrium for acetic acid + water + ( n-propyl acetate or iso-butyl acetate)
Isobaric vapor¢liquid equilibrium (VLE) data for acetic acid+water, acetic acid+n-propyl acetate, acetic acid+iso-butyl acetate, acetic acid+water+n-propyl acetate, acetic acid+water+iso-butyl acetate are measured at 101.33kPa with a modified Rose still. The nonideal behavior in vapor phase caused by the association of acetic acid are corrected by the chemical theory and Hayden¢OÆConnell method, and analyzed by calculating the second virial coefficients and
Chundong Zhang; Hui Wan; Lijun Xue; Guofeng Guan
Preparation and properties of polyvinyl alcohol microspheres
Polyvinyl alcohol (PVA) microspheres, having a size range of approx.150- to 250-..mu..m diameter with 1- to 5-..mu..m wall thickness, have been fabricated using a solution droplet technique. The spheres were developed for possible use on the Lawrence Livermore National Laboratory (LLNL) Inertial Confinement Fusion (ICF) Program. PVA, a polymer chosen based on earlier survey work carried out at KMS Fusion, Inc., has good strength, low hydrogen permeability, is optically transparent, and water soluble. The latter property makes it safe and easy to use in our droplet generator system. A unique dual-orifice droplet generator was used to prepare the spheres. The droplet generator operating conditions and the column processing parameters were chosen using results from our 1-D model calculations as a guide. The polymer microsphere model is an extension of the model we developed to support the glass sphere production. After preparation, the spheres were physically characterized for surface quality, sphericity, wall thickness (and uniformity), and size. We also determined the buckling pressure for both uncoated and CH-coated spheres. Radiation stability to beta decay (from tritium) was evaluated by exposing the spheres to a 7-keV electron beam. The results from these and other physical property measurements are presented in this report.
Campbell, J.H.; Grens, J.Z.; Poco, J.F.; Ives, B.H.
Piezoresistive Properties of Polyvinyl Chloride Composites
Textile based sensors provide an interface between the user and the electronic system by converting any type of physiological or environmental signal into electrical signals. Common applications include health monitoring, rehabilitation, multimedia, and surveillance. In this research we demonstrate fabrication of piezoresistive sensors on textile fabrics through application of a screen-printed conductive nanocomposite layer of plasticized poly(vinyl chloride) (PVC), and carbon nanofiber (CNF). In order to understand the behavior of conductive plastisol, morphological, mechanical and electrical properties of composite films were investigated for different molecular weights of PVC. Homogeneous filler dispersion and good filler/polymer interphase were observed without any dominant filler orientation. Mechanical and electrical properties were found to be affected by CNF, plasticizer content and matrix molecular weight. CNFs were found to provide substantial bridging in the matrix and enhance strength. These nanostructured composite sensors were found to be sensitive under different levels of strain which can be monitored by change in electrical resistance. Finally, we demonstrate the fabrication of piezoresistive sensors on textile fabrics through application of a screen-printed conductive nanocomposite layer of conductive plastisol. Conductive plastisol was found to show good adhesion to fabric with homogeneous CNF distribution. As in composite films, samples were found to show negative piezoresistance at different levels of strain. Strain level and filler concentration were found to affect the piezoresistive behavior and sensitivity of the printed sensors.
Toprakci, Hatice Aylin Karahan
[Nomegestrol acetate: clinical pharmacology].
Progestogens are used in clinical practice in some conditions. Their effects depend on their chemical structure, pharmacokinetics, pharmacodynamics, with important differences among various progestogens. Generally, progestins are classified according to their parent molecule, of which often they keep some features. Derivatives of 19-nor-progesterone are characterized by high selectivity of action on progestin receptor. In particular, nomegestrol acetate (NomAc) shows an important progestational potency, neutral gluco-lipid profile, and antigonadotropic activity. It is used for treating menstrual cycle disorders and for hormone replacement therapy in menopause in association with an estrogen. In future, thanks to its antigonadotropic activity, NomAc will be used in estroprogestin combinations in fertile women, thus taking advantage of its tolerability profile and obtaining numerous non-contraceptive benefits as well. PMID:19749678
Lello, S
Thermogravimetric analysis of the relationship among calcium magnesium acetate, calcium acetate and magnesium acetate
Thermal decomposition characteristic of calcium magnesium acetate (CMA), calcium acetate (CA) and magnesium acetate (MA) are investigated through thermogravimetric (TG) analysis at the heating rates of 5Kmin?1, 7.5Kmin?1, 10Kmin?1 and 15Kmin?1. After dehydration, the evaporation of carboxylic radical and carbon dioxide of CMA and CA exist in two separate segments, but for MA, this occurs together in just one segment
Shengli Niu; Kuihua Han; Chunmei Lu; Rongyue Sun
Biodegradability of poly(3-hydroxybutyrate) film grafted with vinyl acetate: Effect of grafting and saponification
Radiation-induced graft polymerization of vinyl acetate (VAc) onto poly(3-hydroxybutyrate) (PHB) film was carried out. At a degree of grafting higher than 5%, the grafted films (PHB-g-VAc) completely lost the enzymatic degradability that is characteristic of PHB due to the grafted VAc covering the surface of the PHB film. However, the biodegradability of the PHB-g-VAc films was recovered when the films were saponified in alkali solution under optimum conditions. Graft chains of the PHB-g-VAc film reacted selectively to become biodegradable polyvinyl alcohol (PVA). The biodegradability of the saponified PHB-g-VAc film increased rapidly with time.
Wada, Yuki; Seko, Noriaki; Nagasawa, Naotsugu; Tamada, Masao; Kasuya, Ken-ichi; Mitomo, Hiroshi
Nanodielectric mapping of a model polystyrene-poly(vinyl acetate) blend by electrostatic force microscopy.
We present a simple method to quantitatively image the dielectric permittivity of soft materials at nanoscale using electrostatic force microscopy (EFM) by means of the double pass method. The EFM experiments are based on the measurement of the frequency shifts of the oscillating tip biased at two different voltages. A numerical treatment based on the equivalent charge method allows extracting the values of the dielectric permittivity at each image point. This method can be applied with no restrictions of film thickness and tip radius. This method has been applied to image the morphology and the nanodielectric properties of a model polymer blend of polystyrene and poly(vinyl acetate). PMID:20365314
Riedel, C; Arinero, R; Tordjeman, Ph; LķvĻque, G; Schwartz, G A; Alegria, A; Colmenero, J
Nanodielectric mapping of a model polystyrene-poly(vinyl acetate) blend by electrostatic force microscopy
We present a simple method to quantitatively image the dielectric permittivity of soft materials at nanoscale using electrostatic force microscopy (EFM) by means of the double pass method. The EFM experiments are based on the measurement of the frequency shifts of the oscillating tip biased at two different voltages. A numerical treatment based on the equivalent charge method allows extracting the values of the dielectric permittivity at each image point. This method can be applied with no restrictions of film thickness and tip radius. This method has been applied to image the morphology and the nanodielectric properties of a model polymer blend of polystyrene and poly(vinyl acetate).
Riedel, C.; Arinero, R.; Tordjeman, Ph.; LķvĻque, G.; Schwartz, G. A.; Alegria, A.; Colmenero, J.
Stabilized Calcium Acetate Oil Dispersions.
A lubricating composition is imparted with improved load-carrying ability and anti-wear properties by incorporation of calcium acetate. The composition consists of a base lubricant, 0.1 to 50 percent by weight calcium acetate and 0.01 to 20 percent by wei...
R. H. Davis
[Formulation of calcium acetate tablets].
The results of the testing of calcium acetate tablets, produced by direct compression and by wet granulation (Ph. Jug. IV) are presented. Tablet hardness, friability and disintegration were determined. The best properties were observed in the tablets produced with maize starch. This procedure is fast and simple, and compound tablets of calcium acetate fulfill the current requirements for this type of preparation. PMID:11521467
Obrenovic, D; Gazikalovic, E; Ognjanovic, J; Nidzovic Z, Z
...false Emission standard for polyvinyl chloride plants. 61.64 Section 61.64 ...National Emission Standard for Vinyl Chloride ┬¦ 61.64 Emission standard for polyvinyl chloride plants. An owner or operator of a...
Molecular Structure of Phenylmercuric acetate
NSDL National Science Digital Library
Phenylmercuric acetate is white to white-yellow crystalline powder that is odorless. This phenyl mercury compound is used mainly as a fungicide, herbicide, slimicide and bacteriocide. Phenylmercuric acid serves as a preservative in canned paint, eye ointments and drops, injectable solutions, skin disinfectants and in cosmetics products such as hair shampoos, mouthwashes and toothpastes. It is also used in contraceptive gels and foams. Phenylmercuric acetate is prepared by interaction of benzene with mercuric acetate in glacial acetic acid. Phenylmercuric acetate's former production and use as a fungicide and as a mildew inhibitor in paints may have resulted in its direct release to the environment. This substance is very toxic to aquatic organisms and may be hazardous to the environment.
Reactions between vinyl compounds and multifunctional compounds communication 2. Reactions of vinyl ethers with polyvinyl alcohol
Summary 1.A study has been made of the reactions between polyvinyl alcohol and butyl vinyl and phenyl vinyl ethers, the proportions of components being varied.2.It has been shown that reaction between polyvinyl alcohol and butyl vinyl or phenyl vinyl ether leads to the formation of polyacetals of polyvinyl alcohol.3.It is possible that the formation of the polyacetals of polyvinyl alcohol
M. F. Shostakovsky; V. V. Zhebrovsky; M. A. Medelyanovskaya
Triamcinolone acetonide acetate.
IN THE CRYSTAL STRUCTURE OF THE TITLE COMPOUND [SYSTEMATIC NAME: 2-(4b-fluoro-5-hy-droxy-4a,6a,8,8-tetra-methyl-2-oxo-2,4a,4b,5,6,6a,9a,10,10a,10b,11,12-dodeca-hydro-7,9-dioxa-penta-leno[2,1-a]phenanthren-6b-yl)-2-oxoethyl acetate], C(26)H(33)FO(7), the mol-ecules are connected by inter-molecular O-H?O hydrogen bonds into an infinite supra-molecular chain along the b axis. The mol-ecular framework consists of five condensed rings, including three six-membered rings and two five-membered rings. The cyclo-hexa-2,5-dienone ring is nearly planar [maximum deviation = 0.013?(3)?┼], while the cyclo-hexane rings adopt chair conformations. The two five-membered rings, viz. cyclo-pentane and 1,3-dioxolane, display envelope conformations. PMID:21523039
Lu, Xiao; Tang, Gu-Ping; Gu, Jian-Ming; Hu, Xiu-Rong
Triamcinolone acetonide acetate
In the crystal structure of the title compound [systematic name: 2-(4b-fluoro-5-hyŁdroxy-4a,6a,8,8-tetraŁmethyl-2-oxo-2,4a,4b,5,6,6a,9a,10,10a,10b,11,12-dodecaŁhydro-7,9-dioxaŁpentaŁleno[2,1-a]phenanthren-6b-yl)-2-oxoethyl acetate], C26H33FO7, the molŁecules are connected by interŁmolecular OŚH?O hydrogen bonds into an infinite supraŁmolecular chain along the b axis. The molŁecular framework consists of five condensed rings, including three six-membered rings and two five-membered rings. The cycloŁhexa-2,5-dienone ring is nearly planar [maximum deviation = 0.013?(3)?┼], while the cycloŁhexane rings adopt chair conformations. The two five-membered rings, viz. cycloŁpentane and 1,3-dioxolane, display envelope conformations.
Preparation and characterization of polyvinyl alcohol---chitosan biocompatible magnetic microparticles
This work addresses the obtaining of biocompatible magnetic polyvinyl alcohol---chitosan microspheres, specifically tailored\\/functionalised to bind directly blood toxins using an emulsion crosslinking preparation method. The following synthesis parameters were studied: water to oil phase ratio, polyvinyl alcohol molecular weight, chitosan to polyvinyl alcohol weight ratio, surfactant composition and concentration of the crosslinking agent. These parameters were optimized for producing a
Laura Elena Udrea; Doina Hritcu; Marcel Ionel Popa; Ovidiu Rotariu
Preparation and characterization of polyvinyl alcoholŚchitosan biocompatible magnetic microparticles
This work addresses the obtaining of biocompatible magnetic polyvinyl alcoholŚchitosan microspheres, specifically tailored\\/functionalised to bind directly blood toxins using an emulsion crosslinking preparation method. The following synthesis parameters were studied: water to oil phase ratio, polyvinyl alcohol molecular weight, chitosan to polyvinyl alcohol weight ratio, surfactant composition and concentration of the crosslinking agent. These parameters were optimized for producing a
Evaluation of an Environmentally Friendly Plasticizer For Polyvinyl Butyral For Use in Tape Casting
An environmentally friendly plasticizer for polyvinyl butyral has been evaluated and compared with the industry standard - butyl benzyl phthalate. Properties such as the effect on the glass transition temperature of polyvinyl butyral and its compatibility with several grades of polyvinyl butyral are discussed. A direct comparison of this plasticizer is made with the industry standard in side-by-side tape casting
Richard E. Mistler; Ernest Bianchi; Bruce Wade; Jeffrey Hurlbut
The Polyvinyl Alcohol Sponge Model Implantation
Wound healing is a complicated, multistep process involving many cell types, growth factors and compounds1-3. Because of this complexity, wound healing studies are most comprehensive when carried out in vivo. There are many in vivo models available to study acute wound healing, including incisional, excisional, dead space, and burns. Dead space models are artificial, porous implants which are used to study tissue formation and the effects of substances on the wound. Some of the commonly used dead space models include polyvinyl alcohol (PVA) sponges, steel wire mesh cylinders, expanded polytetrafluoroethylene (ePTFE) material, and the Cellstick1,2. Each dead space model has its own limitations based on its material's composition and implantation methods. The steel wire mesh cylinder model has a lag phase of infiltration after implantation and requires a long amount of time before granulation tissue formation begins1. Later stages of wound healing are best analyzed using the ePTFE model1,4. The Cellstick is a cellulose sponge inside a silicon tube model which is typically used for studying human surgery wounds and wound fluid2. The PVA sponge is limited to acute studies because with time it begins to provoke a foreign body response which causes a giant cell reaction in the animal5. Unlike other materials, PVA sponges are easy to insert and remove, made of inert and non-biodegradable materials and yet are soft enough to be sectioned for histological analysis2,5. In wound healing the PVA sponge is very useful for analyzing granulation tissue formation, collagen deposition, wound fluid composition, and the effects of substances on the healing process1,2,5. In addition to its use in studying a wide array of attributes of wound healing, the PVA sponge has also been used in many other types of studies. It has been utilized to investigate tumor angiogenesis, drug delivery and stem cell survival and engraftment1,2,6,7. With its great alterability, prior extensive use, and reproducible results, the PVA sponge is an ideal model for many studies1,2. Here, we will describe the preparation, implantation and retrieval of PVA sponge disks (Figure 1) in a mouse model of wound healing.
Deskins, Desirae L.; Ardestani, Shidrokh; Young, Pampee P.
[Pulmonary manifestations of polyvinyl chloride exposure].
There is currently no national data on the effects of polyvinyl chloride (PVC) exposure on pulmonary function. In this study we recruited workers and administrative staff from two PVC plants between July 2008 and July 2009. A questionnaire, pulmonary function tests, carbon monoxide diffusion capacity, and peak flows were recorded. Particulate matter analyses were performed by the Adana Central Laboratory of the Directorate of Occupational Health and Safety. Data were analyzed with SPSS 13.0 software. Nine of the 147 subjects were female. The incidence of a cough was more common in the administrative group. Of the study population, 59.1% were smokers. Tobacco addiction significantly increased cough and dyspnea [OR= 1.10 (1.00-1.20, 95% CI) p= 0.007 and OR= 1.08 (1.02-1.14, 95% CI), p= 0.008, respectively]. Dust exposure was correlated with the incidence of a cough [OR= 0.20 (0.04-0.80, 95% CI) p= 0.008]. The period of work correlated with sputum production [OR= 1.00 (1.00-1.02, 95% CI) p= 0.044]. The FVC% was significantly higher in the administrative group, and FEV1/FVC and DLCO were higher in the exposed group. Tobacco addiction increased the risk of airflow limitation, as evaluated by FEV1/FVC < 70% and FEF25-75 < 50% [OR= 1.15 (1.06-1.25, 95% CI) p= 0.001 and OR= 1.09 (1.02-1.17, 95% CI) p= 0.010, respectively]. Tobacco addiction and increasing duration of work had a negative influence on DLCO in the exposed group (r= -0.270, p= 0.025 and r= -0.210, p= 0.037). In the exposed group PEF variability was significantly greater on workdays, compared with rest days. This study shows that tobacco consumption has a greater affect on the airways than PVC dust exposure. A median of 36 months exposure to PVC dust had no significant impact on pulmonary function parameters, except for DLCO and PEF variability. PMID:21554225
S³y³r, H³seyin; Bayram, Nazan; Ayd?n, Neriman; Uyar, Meral; G³ndo?du, Nevhiz; Elbek, Osman
Molecular Structure of Sodium acetate
Sodium acetate is known for its ability to supercool. It freezes at 130 degrees, but can exist as a liquid at a much lower temperature. In order to melt solidified sodium acetate, however, every single crystal must liquify, otherwise the material will recrystallize. Sodium acetate has been used as a deicer for roads and runways. It is also used a component of buffer systems and in the manufacture of pharmaceuticals and heat pads. The compound is quite stable. It may act as an irritant and be harmful if inhaled or absorbed through the skin.
Effect of natural gas odorants on polyvinyl chloride pipe
From studies of the effect of natural gas odorants on polyvinyl chloride and polyethylene pipe, the University of Saskatchewan and the Saskatchewan Power Corp. conclude that PE pipe is not affected by the odorants, while the mechanical strength of PVC pipe is affected by some. After 10-day exposures to liquid mercaptan-based odorants, the PE samples showed no physical changes and
A. R. Knight; A. Verma
Gel Drawn Fibers of Poly(Vinyl Alcohol).
Semi-crystalline gels of several samples of poly(vinyl alcohol) were made from solutions in which the polymer concentration varied from 2.0 to 15.0%. Entanglement density in the material was in this way reduced from the melt entanglement density. When gel...
P. Cebe D. T. Grubb
Biodegradation of polyvinyl alcohol by a mixed microbial culture
A mixed culture capable of degrading 1gl?1 polyvinyl alcohol (PVA) completely was screened from sludge samples at Pacific Textile Factory, Wuxi, China. This mixed culture had stronger capability of degrading PVA with low polymerization and high saponification than degrading PVA with high polymerization and low saponification. Inorganic nitrogen source was more suitable for the mixed culture to grow and degrade
Jian Chen; Ying Zhang; Guo-Cheng Du; Zhao-Zhe Hua; Yang Zhu
Dielectric Properties and Side-Chain Crystallinity of Polyvinyl Stearate
Measurements of the real (&egr;?) and imaginary (&egr;?) parts of the dielectric constant have been made on polyvinyl stearate at temperatures from ?50░ to +80░C and over a frequency range from 100 to 50 000 cps. Although no full relaxation dispersion region has been found in this frequency range, there are indications of the beginnings of a high-frequency dispersion region
Martin G. Broadhurst; Edwin R. Fitzgerald; Anthony J. Bur
Biodegradation of a polyvinyl alcohol-starch blend plastic film
Attempts were made to elucidate the degradation mechanism of a polyvinyl alcohol (PVA)-starch blend plastic. A part of the starch fraction of this plastic was dissolved into an aqueous phase in a control test. Treatment with a PVA-degrading bacterium or enzyme gave a maximal weight loss of approximately 70% and film breakage occurred. Since this plastic contains 40% PVA, it
Tomonori Ishigaki; Yasunori Kawagoshi; Michihiko Ike; Masanori Fujita
Crack formation in polyvinyl chloride coatings on underground pipes
and certain other agents, for a polymeric coating on a tube in the soil, other specific features are also characteristic. Results have previously been presented [1, 2] of a study of polyvinyl chloride coatings kept for a prolonged period under different underground conditions. The investigations were concerned with oxidative processes under the influence of the molecular oxygen of the air
B. I. Borisov; CHLORIDE COATINGS
Plasticized Poly(Vinyl Chloride) Filled with Waste Leather Particles
Waste leather granules were incorporated into poly(vinyl chloride) polymer plasticized with di-octyl phthalate. The blend was prepared by a melt mixing process using a banbury mixer. The rheological behaviour of the mixture was recorded and the filled samples were tested for their physicomechanical properties. It was found that density, wear resistance and Shore D hardness of the specimen increases, whereas
K. Babanas; P. A. Tarantili; A. G. Andreopoulos
Luminescent properties of polyvinyl alcohol Ś inorganic salt compositions
Spectral and luminescent properties of polyvinyl alcohol (PVA) films with alkali-halide salt additives are investigated in the present work. The observed effect of increasing the luminescence brightness for the given compositions is explained by the interaction of vacancy defects with polymer macromolecules during their adsorption on salt microcrystals.
Suchkova, E. N.; Pagubko, A. B.
Dynamic Tangent Moduli of Polyvinyl Chloride Subjected to Large Strains.
The data present in this report describe the changes in the linear dynamic viscoelastic properties of polyvinyl chloride when it has been subjected to large one-dimensional strains. Dynamic tests were carried out on specimens which had undergone large qua...
B. J. Reilly
This report presents a model to predict worker inhalation exposure due to off-gassing of additives during polyvinyl chloride (PVC) extrusion processing. ata on off-gassing of additives were reviewed in the literature, the off-gassing at normal PVC processing temperatures was stud...
Immobilization of enzymes in photochemically cross-linked polyvinyl alcohol
Invertase and amyloglucosidase were entrapped in polyvinyl alcohol membranes through UV irradiation of pendent styrylpyridinium groups. The influence of cross-linking on immobilization efficiency was studied using prepolymers with varied cross-linker density, the above mentioned enzymes of different molecular weight, and various substrates. It was found that the larger enzyme invertase is effectively immobilized even in polymers with very low contents
Thomas Uhlich; Mathias Ulbricht; Georg Tomaschewski
Acetate catabolism by Methanosarcina barkeri
Cell suspensions of Methanosarcina barkeri convert the carboxyl and methyl group carbons of acetate to carbon dioxide and methane at pH 6 under an atmosphere of 100% CO/sub 2/. The rate of loss of radioactivity from (1-/sup 14/C)acetate was over three times greater than that from (2-/sup 14/C)acetate under these conditions. Control experiments with both labeled substrates present showed that the rates were additive. Addition of a high level of 2-bromoethanesulfonate to selectively inhibit methane formation largely inhibited release of /sup 14/C from methyl-labeled acetate but only marginally decreased the rate of loss from (1-/sup 14/C)acetate. Thus, in the absence of the inhibitor loss of /sup 14/C from (1-/sup 14/C)acetate likely reflects an isotopic exchange reaction with CO/sub 2/ superimposed on the overall conversion of acetate to CO/sub 2/ and CH/sub 4/. The exchange reaction was inhibited by uncouplers such as 2,4-dinitrophenol, CCCP, and FCCP. Cells permeabilized by treatment with nonionic detergents or disrupted by passage through a French pressure cell failed to catalyze the exchange reaction. Exchange activity was not restored by addition of ATP or by use of (1-/sup 14/C)acetyl CoA as substrate. No evidence for involvement of carbon monoxide dehydrogenase in the exchange was found in these experiments when CO/sub 2/ was replaced by CO. However, the soluble extracts retained the ability to convert acetate to methane in the presence of H/sub 2/ and ATP.
Grahame, D.A.
Electrically Conducting Polymer-Copper Sulphide Composite Films, Preparation by Treatment of Polymer-Copper (2) Acetate Composites with Hydrogen Sulfide
Polymer copper sulfide composite films were prepared by treatment of polymer poly(vinyl chloride), poly(acrylonitrile), copolymer of vinyl chloride and vinyl acetate (90:10), and ABS resin copper (2) acetate composites with hydrogen sulfide. The films showed electrical conductivity higher than 0.015 S/cm when they contained more than 20 wt percent of copper sulfide. A poly(acrylonitrile)-copper sulfide composite film containing 40 to 50 wt percent of copper sulfide showed electrical conductivity of 10 to 150.0 S/cm and had relatively high mechanical strength to be used in practical purposes.
Yamamoto, Takakazu; Kamigaki, Takahira; Kubota, Etsuo
Investigation on isobaric vapor¢liquid equilibrium for acetic acid + water + methyl ethyl ketone + isopropyl acetate
Isobaric vapor¢liquid equilibrium (VLE) data for acetic acid+water, acetic acid+methyl ethyl ketone (MEK), MEK+isopropyl acetate, acetic acid+MEK+water and acetic acid+MEK+isopropyl acetate+water are measured at 101.33kPa using a modified Rose cell. The nonideal behavior in vapor phase of binary systems measured in this work is analyzed through calculating fugacity coefficients since mixture containing acetic acid deviates from ideal behavior seriously in
Qiang Xie; Hui Wan; MingJuan Han; GuoFeng Guan
High-rate thermomechanical behavior of poly(vinyl chloride) and plasticized poly(vinyl chloride)
A combined experimental and analytical investigation was carried out in order to develop predictive capabilities for the rate-dependent behavior of poly(vinyl chloride) (PVC) and a dioctyl phthalate (DOP)-plasticized PVC, with focus on predicting the thermo-mechanically coupled behavior under high rates of deformation. The two materials were studied experimentally using both dynamic mechanical analysis (DMA) and compression testing over a wide range of strain rates (10 - 4 s - 1 to 2000 s - 1). DMA testing revealed both an ? -transition and a low-temperature ? -transition (-56circC) in the neat PVC; the incorporation of 20wt% DOP in PVC reduced the ? -transition temperature by 54circC, and also suppressed the ? -transition peak. In compression testing, rate-sensitivity transitions were observed in both the neat PVC and the PVC-20wt% DOP compound. The transition in PVC is attributed to the shift of the ? -transition, whereas the transition in the 20wt% DOP blend is due to the rubbery-to-glassy transition as the deformation rate goes from low to high. A constitutive model for the finite strain deformation of amorphous polymers, introduced elsewhere [1,2] and tailored here for the two material systems of interest, is shown to capture the large deformation stress-strain behavior at all rates tested.
Mulliken, A. D.; Soong, S. Y.; Boyce, M. C.; Cohen, R. E.
Micropatterned polyvinyl butyral membrane for acid-base diodes.
Until now, polyvinyl alcohol (PVA) gel cylinders have been used in electrolyte diodes as a connecting element between the acidic and alkaline reservoirs. In this paper, a new connecting element is reported: a breath figure templated polyvinyl butyral (PVB) membrane prepared with dip-coating from a dichloromethane solution of the polymer in a humid atmosphere. The procedure gives a 1.5-2 ?m thick membrane with a hexagonal pattern, the average characteristic length of which is 1 ?m. After an acidic etching, it was found to be a good connecting element. The voltage-current characteristics and dynamic properties of PVA and PVB were measured and compared. The PVB membrane has a faster response to voltage changes than the PVA gel, but in both cases, there was a slow drift in the current that prevented it from reaching a steady state. Reproducible characteristics can be obtained, however, after the current reaches a well-defined quasi-steady state. PMID:20929271
Roszol, Lßszl¾; Lawson, Thuy; Koncz, Vikt¾ria; Noszticzius, Zoltßn; Wittmann, Maria; Sarkadi, Tamßs; Koppa, Pßl
Structure and Properties of Polyvinyl Chloride\\/Halloysite Nanotubes Nanocomposites
Poly(vinyl chloride)(PVC)\\/halloysite nanotubes (HNTs) nanocomposites were prepared by melt blending. The effects of HNT content on the mechanical properties, morphology and rheological properties of the nanocomposites were investigated. The results showed that HNTs were effective in toughening and reinforcing PVC nanocomposites. The notched impact, tensile and flexural strength, and flexural modulus of the nanocomposites were remarkably increased compared to those
Cong Liu; Yuanfang Luo; Zhixin Jia; Shuangquan Li; Baochun Guo; Demin Jia
Investigation of the alumina properties with adsorbed polyvinyl alcohol
The influence of solution pH on the structure of polyvinyl alcohol adsorption layer on the alumina surface was investigated.\\u000a The spectrophotometry, viscosimetry, thermogravimetry, potentiometric titration and microelectrophoresis were applied in experiments.\\u000a These methods enable determination of the following parameters: adsorbed amount of PVA, stability of suspension without and\\u000a with polymer, thickness of its adsorption layers, changes in thermal characteristics of
Ma?gorzata Wi?niewska; Stanis?aw Chibowski; Teresa Urban; Dariusz Sternik
Synthesis of a mesoporous silica hollow microsphere using polyvinyl alcohol
A mesoporous silica hollow microsphere was synthesized in the presence of polyvinyl alcohol for the first time. The synthesized material was characterized by various instrumental techniques such as small-angle X-ray scattering, scanning electron microscopy, transmission electron microscopy, N2 adsorption measurement and Fourier transform infrared spectroscopy. I have succeeded in incorporating an Ultraviolet ray absorber, 2, 2┤, 4, 4┤ tetrahydroxy benzophenone
N. Venkatathri
Poly(vinyl alcohol)\\/cellulose nanocrystal barrier membranes
In this study, barrier membranes were prepared from poly(vinyl alcohol) (PVOH) with different amounts of cellulose nanocrystals (CNXLs) as filler. Poly(acrylic acid) (PAA) was used as a crosslinking agent to provide water resistance to PVOH. The membranes were heat treated at various temperatures to optimize the crosslinking density. Heat treatment at 170░C for 45min resulted in membranes with improved water
Shweta A. Paralikar; John Simonsen; John Lombardi
Immobilization of lipase enzyme in polyvinyl alcohol (PVA) nanofibrous membranes
Lipase enzyme from Candida rugosa (E.C. 188.8.131.52) has been successfully immobolized in 100¢500nm diameter fibers via electrospinning of aqueous mixtures of lipase and polyvinyl alcohol (PVA). Enzyme loading in these bicomponent fibers reached as high as 50%. The catalytic activity of the fiber bound lipase was the same as the crude enzyme, showing no adverse effects from either electric charges
Y. Wang; Y.-L. Hsieh
Immobilization of enzyme into poly(vinyl alcohol) membrane
Glucoamylase, invertase, and cellulase were entrapped within poly(vinyl alcohol) (PVA) membrane cross-linked by means of irradiation of ultraviolet light. The conditions for immobilization of glucoamylase were examined with respect to enzyme concentration in PVA, sensitizer (sodium benzoate) concentration in PVA, irradiation time, and membrane thickness. Various characteristics of immobilized glucoamylase were evaluated. Among them, the pH activity curve for the
Kiyokazu Imai; Tomoo Shiomi; Kozo Uchida; Masamitsu Miya
Preparation and properties of microfibrillated cellulose polyvinyl alcohol composite materials
This work reports the preparation of MFC¢PVA composite films, and the thermal and mechanical properties of these films. Microfibrillated cellulose (MFC), which was separated from kraft pulp by a mechanical process, was used as the reinforcement in polyvinyl alcohol (PVA) matrix. This MFC reinforcement has an interconnected web-like structure with fibrils having a diameter in the range of 10¢100nm, as
Jue Lu; Tao Wang; Lawrence T. Drzal
Migration of plasticizers from plasticized polyvinyl chloride films
The migration of plasticizers [EDOS, di(2-ethyl hexyl) o-phthalate, di-n-butyl o-phthalate] from unfilled and chalk-filled polyvinyl chloride films plasticized with individual and binary plasticizers was\\u000a studied by gravimetric analysis and IR spectroscopy. The intermolecular interaction of components in model systems was studied\\u000a by IR spectroscopy and isothermal calorimetry.
B. I. Lirova; E. A. Lyutikova; A. P. Safronov; T. V. Terziyan; B. A. Berkuta; S. I. Degtyarev; M. I. Prusskii
Manufacturing Process and Application of Pseudo-thermoplastic Polyvinyl Alcohol
Polyvinyl alcohol (PVA) has too close melting and degradation temperatures which causes the failure of temperature control during processing. This study uses glycerin as plasticizing agent to improve high thermo-melting property of PVA so that PVA can be processed at a thermo-melt temperature of 190░C and be equipped with the pseudo-thermoplastic characteristic. The PVA processed with this method is called
Chin-An Lin; Hsiao-Chi Tsai; Te-Hsing Ku
Optical nonlinearity of ZnS-polyvinyl pyrrolidone nanocomposite suspension
ZnS-polyvinyl pyrrolidone nanocomposite was prepared by a simple wet-chemical route. TEM and x-ray diffraction confirmed the formation of nanometre size ZnS particles within the polymer matrix. The average particle size was between 10 and 12 nm. The third-order susceptibility chi(3) of the nanocomposite suspension was measured by employing a single beam z-scan setup with 38 ps laser pulses at 532
Cunxiu Wang; Liusan Guan; Yanli Mao; Yuzong Gu; Junhui Liu; Shishu Fu; Qinghai Xu
Structural-mechanical and thermophysical properties of modified polyvinyl chloride
On the basis of a systematic investigation of the viscoelastic properties of polyvinyl chloride filled with waste from mineral fertilizer and phosphoric acid production in the form of highly dispersed phospho-gypsum, the specific heat is calculated and the energy of interaction of the structural elements of the system matrix is determined, together with the effective thermal conductivity coefficient, with allowance for energy dissipation by the elements of the structure.
Bordyuk, N. A.; Bestyuk, Yu. N.; Nikitchuk, V. I.; Kolupaev, B. S.
Stimuli-Responsive Mechanically Adaptive Polymer Nanocomposites
A new series of biomimetic stimuli-responsive nanocomposites, which change their mechanical properties upon exposure to physiological conditions, was prepared and investigated. The materials were produced by introducing percolating networks of cellulose nanofibers or ōwhiskersö derived from tunicates into poly(vinyl acetate) (PVAc), poly(butyl methacrylate) (PBMA), and blends of these polymers, with the objective of determining how the hydrophobicity and glass-transition temperature (Tg) of the polymer matrix affect the water-induced mechanically dynamic behavior. Below the Tg (~60¢70 ░C), the incorporation of whiskers (15.1 ¢ 16.5% v/v) modestly increased the tensile storage moduli (E?) of the neat polymers from 0.6 to 3.8 GPa (PBMA) and from 2 to 5.2 GPa (PVAc). The reinforcement was much more dramatic above Tg, where E? increased from 1.2 to 690 MPa (PVAc) and ~1 to 1.1 GPa (PBMA). Upon exposure to physiological conditions (immersion in artificial cerebrospinal fluid, ACSF, at 37 ░C) all materials displayed a decrease of E?. The most significant contrast was seen in PVAc; for example the E? of a 16.5% v/v PVAc/whisker nanocomposite decreased from 5.2 GPa to 12.7 MPa. Only a modest modulus decrease was measured for PBMA/whisker nanocomposite; here the E? of a 15.1% v/v PBMA/whisker nanocomposite decreased from 3.8 to 1.2 GPa. A systematic investigation revealed that the magnitude of the mechanical contrast was related to the degree of swelling with ACSF, which was shown to increase with whisker content, temperature, and polarity of the matrix (PVAc > PBMA). The mechanical morphing of the new materials can be described in the framework of both the percolation and Halpin-Kardos models for nanocomposite reinforcement, and is the result of changing interactions among the nanoparticles and plasticization of the matrix upon swelling.
Shanmuganathan, Kadhiravan; Capadona, Jeffrey R.; Rowan, Stuart J.; Weder, Christoph
Solution spinning of high-? oxide superconductors: part VII. The effect of polyvinyl alcohol spinning medium on the sintering of ? superconducting filaments
As basic research for the solution spinning of high-0953-2048/9/5/005/img8 oxide superconductor, the effect of poly(vinyl alcohol) (PVA) spinning medium on the sintering of 0953-2048/9/5/005/img9 filament was examined. A precursor filament was produced by dry-spinning starting from a homogeneous aqueous PVA solution of Y, Ba and Cu acetates. The as-drawn filament was pyrolysed to remove volatile components and sintered to generate a superconducting phase. The degree of polymerization (DP) of PVA and the content of acetates in the precursor filament affected the 0953-2048/9/5/005/img10 of the sintered filament. Although most filaments exhibited high 0953-2048/9/5/005/img10 greater than 0953-2048/9/5/005/img12 at 77 K and 0 T, superconductivity above 77 K was not observed for the filament spun from PVA solution of DP=2450 with [acetates]/[PVA]=2 and sintered at 900 and 0953-2048/9/5/005/img13C for 15 min. The filament had a dense structure due to liquid phase sintering. The filament with high 0953-2048/9/5/005/img10 had a skin - core structure, and the highest 0953-2048/9/5/005/img10 of 0953-2048/9/5/005/img16 at 77 K and 0 T was attained for the filament from DP=3500 with [acetates]/[PVA]=4.
Tomita, Hisayo; Goto, Tomoko; Takahashi, Kiyohisa
Performance of materials and their compatibility determine the size of the electrical insulation in power equipment. For this reason dielectric properties of electrical insulation materials are needed for low temperature power applications. In this work we report the dielectric properties of four polymers: polyvinyl alcohol (PVA), poly(methyl methacrylate) (PMMA), polyvinyl butyral resin (PVB), and polyimide (PI--Kapton\\textregistered). The dielectric measurements are performed with an electrical impedance analyzer in the frequency domain. The impedances are recorded in a cryocooler in the temperature range from 45K to 350K. The dielectric breakdown characteristics of the polymers are measured in a liquid nitrogen bath at atmospheric pressure. It is observed that PI and \\pmma\\ dissolved in toluene have the lowest dielectric losses for temperatures lower than $100\\ \\kelvin$. \\Blx\\ and PI have the smallest spread in their breakdown strength data.
Tuncer, Enis [ORNL; Sauers, Isidor [ORNL; James, David Randy [ORNL; Ellis, Alvin R [ORNL
Dielectric Properties of Polyvinyl Alcohol, Poly(methyl Methacrylate), Polyvinyl Butyral Resin and Polyimide at Low Temperatures
Performance of materials and their compatibility determine the size of the electrical insulation in power equipment. For this reason dielectric properties of electrical insulation materials are needed for low temperature power applications. In this work we report the dielectric properties of four polymers: polyvinyl alcohol (PVA), poly(methyl methacrylate) (PMMA), polyvinyl butyral resin (PVB), and polyimide (PI-Kapton«). The dielectric measurements are performed with an electrical impedance analyzer in the frequency domain. The impedances are recorded in a cryocooler in the temperature range from 45 K to 350 K. The dielectric breakdown characteristics of the polymers are measured in a liquid nitrogen bath at atmospheric pressure. It is observed that PI and PMMA dissolved in toluene have the lowest dielectric losses for temperatures lower than 100 K. PVB and PI have the smallest spread in their breakdown strength data.
Tuncer, Enis; Sauers, Isidor; James, D. Randy; Ellis, Alvin R.
Regeneration of Cellulose Acetate Membranes.
Several simple methods for in situ one-step regeneration of both flux and salt-retention properties of service-deteriorated membranes have been developed. Membranes have been successfully regenerated using hot, 4% acetic acid, and a one-step cleaning meth...
P. A. Cantor W. S. Higley C. W. Saltonstall
Lead Acetate, Teratology Study - Rabbits.
Three groups of 15 females rabbits were mated. Two groups were fed lead acetate in their diet at lead concentrations of 54.6 and 546 ppm from day 6 through day 16 of their gestation period. The third group of females and all males received the basal labor...
D. C. Jessup
Biofiltration of ethyl acetate and amyl acetate using a composite bead biofilter.
Biodegradation kinetic behaviors of ethyl acetate and amyl acetate in a composite bead biofilter were investigated. The composite bead was the spherical PVA/peat/KNO3/GAC composite bead which was prepared in our previous works. Both microbial growth rate and biochemical reaction rate were inhibited at higher inlet concentration. For the microbial growth process, the microbial growth rate of ethyl acetate was greater than that of amyl acetate in the inlet concentration range of 100-400ppm. The degree of inhibitive effect was almost the same for ethyl acetate and amyl acetate in this concentration range. The half-saturation constant Ks values of ethyl acetate and amyl acetate were 16.26 and 12.65ppm, respectively. The maximum reaction rate Vm values of ethyl acetate and amyl acetate were 4.08 and 3.53gCh(-1)kg(-1) packed material, respectively. Zero-order kinetic with the diffusion limitation could be regarded as the most adequate biochemical reaction model. For the biochemical reaction process, the biochemical reaction rate of ethyl acetate was greater than that of amyl acetate in the inlet concentration range of 100-400ppm. The inhibitive effect for ethyl acetate was more pronounced than that for AA in this concentration range. The maximum elimination capacity of ethyl acetate and amyl acetate were 82.3 and 37.93gCh(-1)m(-3) bed volume, respectively. Ethyl acetate degraded by microbial was easier than amyl acetate did. PMID:18445522
Chan, Wu-Chung; Su, Mei-Qi
Carbon-isotopic analysis of dissolved acetate
Heating of dried, acetate-containing solids together with oxalic acid dihydrate conveniently releases acetic acid for purification by gas chromatography. For determination of the carbon-isotopic composition of total acetate, the acetate-containing zone of the chromatographic effluent can be routed directly to a combustion furnace coupled to a vacuum system allowing recovery, purification, and packaging of CO2 for mass-spectrometric analysis. For analysis of methyl carbon, acetic acid can be cryogenically trapped from the chromatographic effluent, then transferred to a tube containing excess NaOH. The tube is evacuated, sealed, and heated to 500 degrees C to produce methane by pyrolysis of sodium acetate. Subsequent combustion of the methane allows determination of the 13C content at the methyl position in the parent acetate. With typical blanks, the standard deviation of single analyses is less than 0.4% for acetate samples larger than 5 micromoles. A full treatment of uncertainties is outlined.
Gelwicks, J. T.; Hayes, J. M.
Ozone decomposition in aqueous acetate solutions
The acetate radical ion reacts with ozone with a rate constant of k = (1.5 +/- 0.5) x 10Z dmT mol s . The products from this reaction are CO2, HCHO, and O2 . By subsequent reaction of the peroxy radical with ozone the acetate radical ion is regenerated through the OH radical. A chain decomposition of ozone takes place. It terminates when the acetate radical ion reacts with oxygen forming the unreactive peroxy acetate radical. The chain is rather short as oxygen is developed, as a result of the ozone consumption. The inhibiting effect of acetate on the ozone decay is rationalized by OH scavenging by acetate and successive reaction of the acetate radical ion with oxygen. Some products from the bimolecular disappearance of the peroxy acetate radicals, however, react further with ozone, reducing the effectiveness of the stabilization.
Sehested, K.; Holcman, J.; Bjergbakke, E.; Hart, E.J.
Heating of dried, acetate-containing solids together with oxalic acid dihydrate conveniently releases acetic acid for purification by gas chromatography. For determination of the carbon-isotopic composition of total acetate, the acetate-containing zone of the chromatographic effluent can be routed directly to a combustion furnace coupled to a vacuum system allowing recovery, purification, and packaging of COŌ for mass-spectrometric analysis. For analysis
Jeffrey T. Gelwicks; J. M. Hayes
21 CFR 184.1185 - Calcium acetate.
, CAS Reg. No. 62-54-4), also known as acetate of lime or vinegar salts, is the calcium salt of acetic acid. It may be produced by the calcium hydroxide neutralization of acetic acid. (b) The ingredient meets the specifications of the Food Chemicals Codex, 3d Ed. (1981),...
Perpendicularly oriented lamellae in poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) blended with an amorphous polymer: ultra-thin to thick films.
The oppositely oriented lamellae in ridge and valley bands of ring-banded spherulites in biodegradable poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) (PHBV) interacting with amorphous poly(vinyl acetate) (PVAc) were examined using polarized-light optical, scanning electron, and atomic-force microscopy techniques (POM, SEM, AFM). Solvent-etching and fracturing were utilized for probing the interior morphology of the large-size ring-banded spherulites in PHBV/PVAc (70/30) blend [T(c) = 110 ░C] films or thick bulk of various thicknesses. SEM analysis revealed that dual ridges of two opposite-oriented lamellae correspond to two-color bands (yellow and blue) of successive rings in POM micrographs. Fracture of thick blend samples further exposed that interior 3D spherulites were composed of sheath-kebab (similar to corrugated board) lamellae of two mutually perpendicular orientations. PMID:23318504
Su, Chean-Cheng; Woo, Eamor M; Hsieh, Ya-Ting
Inspection of United States-Department of Energy (US-DOE) model 9975 nuclear materials shipping package revealed corrosion of the lead shielding that was induced by off-gas constituents from organic components in the package. Experiments were performed to determine the corrosion rate of lead when exposed to off-gas or degradation products of these organic materials. The results showed that the room temperature vulcanizing (RTV) sealant was the most corrosive organic species used in the construction of the packaging, followed by polyvinyl acetate (PVAc) glue. Fiberboard material, also used in the construction of the packaging induced corrosion to a much lesser extent than the PVAc glue and RTV sealant, and only in the presence of condensed water. The results indicated faster corrosion at temperatures higher than ambient and with condensed water. In light of these corrosion mechanisms, the lead shielding was sheathed in a stainless steel liner to mitigate against corrosion.
Subramanian, K; Kerry Dunn, K; Joseph Murphy, J
Inspection of United States-Department of Energy (US-DOE) model 9975 nuclear materials shipping package revealed corrosion of the lead shielding induced by off-gas constituents from organic components in the package. Experiments were performed to determine the corrosion rate of lead when exposed to off-gas or degradation products of these organic materials. The results showed that the room temperature vulcanizing (RTV) sealant was the most corrosive organic species followed by the polyvinyl acetate (PVAc) glue. The fiberboard material induced corrosion to a much lesser extent than the PVAc glue and RTV, and only in the presence of condensed water. The results indicated faster corrosion at temperatures higher than ambient and with condensed water as expected. A corrosion rate of 0.05 mm/year measured for coupons exposed to the most aggressive conditions was recommended as a conservative estimate for use in package performance calculations.
Subramanian, K; Kerry Dunn, K
Continuous microcellular foaming of polyvinyl chloride and compatibilization of polyvinyl chloride and polylactide composites
This dissertation focuses on overcoming existing limitations of WPCs which prevent them from realizing their full market potential. These limitations include: (i) lack of a continuous extrusion process for microcellular foaming of polyvinyl chloride (PVC) and its composites using supercritical fluids to reduce the high density of the WPCs, (ii) need for an efficient coupling agent for WPCs to overcome the poor compatibility between wood and plastic, and (iii) unproven use of wood as a filler for the biopolymer polylactide (PLA) to make "green" composites. These limitations were addressed through experimentation to develop a continuous extrusion process for microcellular foaming, and through surface modification of wood flour using natural coupling agents. The effects of wood flour, acrylic modifier and plasticizer content on the rheological properties of PVC based WPCs were studied using an extrusion capillary rheometer and a two-level factorial design. Wood flour content and acrylic modifier content were the major factors affecting the die swell ratio. Addition of plasticizer decreased the true viscosity of unfilled and filled PVC, irrespective of the acrylic modifier content. However, the addition of acrylic modifier significantly increased the viscosity of unfilled PVC but decreased the composite viscosity. Results of the rheological study were used to set baseline conditions for the continuous extrusion foaming of PVC WPCs using supercritical CO 2. Effects of material composition and processing conditions on the morphology of foamed samples were investigated. Foamed samples were produced using various material compositions and processing conditions, but steady-state conditions could not be obtained for PVC. Thus the relationships could not be determined. Incompatibility between wood flour and PVC was the focus of another study. The natural polymers chitin and chitosan were used as novel coupling agents to improve interfacial adhesion between the polymer matrix and wood fiber. Results indicated that addition of chitin and chitosan significantly increased the flexural properties and storage modulus of PVC WPCs, compared to composites without coupling agent. Significant improvements were attained with 0.5 wt. % chitosan and with 6.67 wt. % chitin. Based on the efficiency of chitosan as a coupling agent for PVC based WPCs, a biodegradable composite using polylactide (PLA) and chitosan was developed. Wood flour (0--40 wt. %) was evaluated as a filler for PLA composites and its effect on mechanical, thermal and chemical properties was studied with and without chitosan (0--10 wt. %). Addition of wood flour significantly increased the flexural and storage moduli of PLA-wood flour composites, but had no effect on glass transition temperature (Tg). Chitosan had no significant effect on any of the properties of the composites studied. Development of an efficient and effective coupling agent for PVC wood composite is a significant development which will increase performance while reducing cost. Wood filled PLA composites can further expand WPCs into applications such as packaging and automotive. Results from these studies have broadened the current knowledge base for WPC products and will be useful in the continued expansion of wood composites technology into a variety of industries.
Shah, Bhavesh
Cation exchange resins from chemically modified poly(vinyl chloride)
Poly(vinyl chloride) has been modified chemically to a cation exchange resin by halogen displacement reactions with phenol sulfonic acid, bisphenol-A sulfonic acid and phenolpthalein sulfonic acid. Ion-exchange capacity, salt-splitting capacity and pH-titration characteristics of these resins have been evaluated. pH-titration behaviour of these resins is consistent with that of a polyfunctional cation-exchanger having pK1=2 and pK2=9¢10 corresponding to -SO3H and
Subrata Moitra; Mukul Biswas
Polyvinyl chloride pneumoconiosis: epidemiological study of exposed workers.
Among 1216 workers who were employed in a polyvinyl chloride production factory and who had had no previous dust exposure elsewhere, 20 cases of pneumoconiosis were found. Chest x-ray abnormalities were characterized by limited profusion, irregular type and low gravity. All 20 workers had been exposed to high PVC dust levels. The chest x-ray changes were observed after a minimum exposure of five years and, in a small percentage of cases, were associated with slight restrictive respiratory function impairments. Moreover, in the whole group of workers 388 cases (31.9%) were found with non-specific x-ray abnormalities mainly related to age and smoking. PMID:469619
Mastrangelo, G; Manno, M; Marcer, G; Bartolucci, G B; Gemignani, C; Saladino, G; Simonato, L; Saia, B
Nanodielectric system for cryogenic applications: Barium titanate filled polyvinyl alcohol
In the current study the focus is on dielectric properties (as a function of frequency and temperature) of a polymeric composite system composed of polyvinyl alcohol and barium titanate nano powder. In the investigations, the temperature range is between 50-295 K, and the frequency range is between $20\\ \\hertz-1\\ \\mega\\hertz$. Polarization and conduction processes are investigated in the linear regime. Dielectric breakdown strengths of samples are also reported. The materials presented have potential to be implemented in cryogenic capacitor or field grading applications.
Tuncer, Enis [ORNL; Sauers, Isidor [ORNL; James, David Randy [ORNL; Ellis, Alvin R [ORNL; Duckworth, Robert C [ORNL
Anomalous ice nucleation behavior in aqueous polyvinyl alcohol solutions
The effect of polymers on the ice nucleation temperature ( Tf) was studied in a W/O emulsion using ś5 ?m diameter droplets by differential scanning calorimetry (DSC). Four types of polymers were used. Among them, only polyvinyl alcohol (PVA) showed the additional effect of increasing the Tf of the aqueous solutions. This increase was logarithmic with the concentration of PVA and the difference in molecular weight did not have any significant effect on Tf for the same weight concentration. It was shown that the number of the structural unit (CH 2CHOH) was the key parameter for the increasing degree of Tf.
Ogawa, S.; Koga, M.; Osanai, S.
Catalytic dehydrochlorination of polyvinyl chloride in two-phase systems
The catalytic activity of quaternary ammonium salts (QAS), whose cation and anion structures are different, and the mechanism of catalytic two-phase dehydrochlorination of polyvinyl chloride (PVC) are studied. Under phase-transfer conditions, dehydrochlorination of PVC is shown to proceed at the interface via an ionic mechanism in the presence of quaternary ammonium salts. The catalytic activity of QAS is governed by both the cation lipophilicity and the anion nature and increases as alcohols are introduced into the reaction mixture. The alcohol nature does not influence the extent of the reaction completion, but it does effect the supermolecular structure of the polyacetylene synthesized.
Leplyanin, G.V.; Salimgareeva, V.N.; Sannikova, N.S. [Institute of Organic Chemistry, Ufa (Russian Federation)
Fumes generated during laser processing of polyvinyl chloride (PVC)
An approach to the assessment of fumes produced in laser material processing is presented. The subsequent design of the fume containment system and sampling strategy is detailed. Polyvinyl chloride (PVC) has been selected for investigation and the complexity resulting from the plethora of additives is discussed. Qualitative results from the preliminary studies of CO 2 laser cutting of PVC are presented together with an appraisal of the problems involved in extending this to quantitative analysis. Benzene, hydrogen chloride (HCl) and methyl methacrylate were found to be the dominant emissions.
Vassie, L. H.; Roach, R. J.; Tyrer, J. R.; Sharp, B. L.
Microwave reflectivity measurement of silicon urea polyvinyl alcohol \\/ epoxy resin composites in X and Ku bands
In the paper presented here, a thermally stable epoxy resin modified urea - polyvinyl alcohol - silicon blends have been prepared by in situ polymerization technique. For this, the materials were modified with triethylene tetramine (hardener) to obtain highly cross-linked thermosetting resins. The authors have synthesized the polymer composites; silicon-urea-polyvinyl alcohol in three ratios in weight percentages with analytical reagent
M. Murugan; V. K. Kokate
Poly(vinyl alcohol) gels for use as tissue phantoms in photoacoustic mammography
Materials for solid photoacoustic breast phantoms, based on poly(vinyl alcohol) hydrogels, are presented. Phantoms intended for use in photoacoustics must possess both optical and acoustic properties of tissue. To realize the optical properties of tissue, one approach was to optimize the number of freezing and thawing cycles of aqueous poly(vinyl alcohol) solutions, a procedure which increases the turbidity of the
Alexei Kharine; Srirang Manohar; Rosalyn Seeton; Roy G. M. Kolkman; Renķ A. Bolt; Wiendelt Steenbergen; Frits F. M. de Mul
Leaching of diethylhexyl phthalate from polyvinyl chloride bags into intravenous cyclosporine solution
The release of diethylhexyl phthalate (DEHP) from flexible polyvinyl chloride containers into intravenous cyclosporine solutions was studied. Intravenous cyclosporine solution or solutions containing the vehicle Cremophor EL and alcohol in dextrose were prepared in an all-glass system and stored in polyvinyl chloride (PVC) bags. Four samples were obtained at different time intervals, and DEHP content was analyzed by gas chromatography.
R. Venkataramanan; G. J. Burckart; R. J. Ptachcinski; R. Blaha; L. W. Logue; A. Bahnson; C. S. Giam; J. E. Brady
Synergetic effect of poly(vinyl butyral) and calcium carbonate on thermal stability of poly(vinyl chloride) nanocomposites investigated by TG¢FTIR¢MS
In order to improve poly(vinyl chloride) (PVC) thermal stability, poly(vinyl butyral) (PVB) matrix and calcium carbonate nanoparticles\\u000a were incorporated in plasticized PVC. Thermal properties of these composites were investigated by thermogravimetry analysis\\u000a coupled with mass spectrometry and Fourier transform infrared spectroscopy (FTIR). This approach highlighted the efficiency\\u000a of both PVB and CaCO3 as HCl scavengers by postponing both the onset
Stķphanie Etienne; Claude Becker; David Ruch; Albert Germain; Cķdric Calberg
Radiation-induced network formation in polyvinyl chloride-polyfunctional monomer systems
Some aspects of the radiation polymerization of allylic polyfunctional monomers in mixtures with polyvinyl chloride have been investigated. The process proceeds through a stepwise formation of the network polymerizate from the polyfunctional monomer, reaction between the polymerizate and polyvinyl chloride and further crosslinking of polyvinyl chloride through reaction with residual allylic double bonds. The initiating radical for the first stage is a low-molecular weight radiolytic product of polyvinyl chloride (apparently, the chloro-radical). At higher initial monomer content the structure formed changes from that of a crosslinked copolymer to that of an interpenetrating network, during irradiation. In the presence of aliphatic plasticizer, the crosslinking density increases in irradiated compositions of polyvinyl chloride and polyfunctional monomers.
Dakin, V. I.
Preparation and application of low molecular weight poly(vinyl chloride). III mechanical properties of blended poly(vinyl chloride)
The blending effect of poly(vinyl chloride) with relatively higher molecular weight (HMW-PVC) and relatively lower molecular weight (LMW-PVC) has been investigated by measuring various mechanical properties: melt properties, tensile strength, tensile modulus, and impact strength. The blended PVC has slightly improved melt properties in comparison with the HMW-PVC used. The tensile strength of the blended PVC is related to the weight-average polymerization degree (Pw) of LMW-PVC and the LMW-PVC content. At the LMW-PVC content of 20%, the tensile strength of blended PVC is a maximum: approximately 58 MPa.
Yamamoto, Kikuo; Maehala, Takashi; Mitani, Katsuo; Mizutani, Yukio (Tokuyama Soda Co., Ltd., Tokuyama-city (Japan))
Utilizing Matrix-Filler Interactions in the Design of Stimuli-Responsive, Mechanically-Adaptive Electrospun Composites
A new class of all-organic, stimuli-responsive and mechanically-adaptive electrospun nanocomposites, which have the ability to alter their stiffness upon hydration, were developed. These materials were fabricated by incorporating an electrospun mat of poly(vinyl alcohol) (PVA) as the filler in a polymeric matrix consisting of either poly(vinyl acetate) (PVAc) or ethylene oxide-epicholorohydrin copolymer (EO-EPI). The incorporation of high stiffness, high aspect ratio PVA filler mat significantly enhanced the tensile storage modulus of EO-EPI based composites, while modulus enhancement was only noticed above the glass transition for PVAc-based composites. Composite materials based on a rubbery EO-EPI host polymer and PVA filler exhibit an irreversible reduction by a factor of 12 of the tensile modulus upon hydration. In contrast, composites comprised of PVAc show a reversible reduction of modulus by a factor of 280 upon water uptake. The mechanical morphing of the electrospun composites is the result of the filler crystallinity, and matrix-filler interactions facilitated by the surface hydroxyl groups of the PVA filler. The choice of polymer matrix and electrospun nanofiber fillers allow control of matrix-filler interactions in a new series of all-organic composites to achieve desired stimuli-responsiveness and mechanical-adaptability upon exposure to various stimuli.
Wanasekara, Nandula; Stone, David; Wnek, Gary; Korley, Lashanda
Soluplus graft copolymer: potential novel carrier polymer in electrospinning of nanofibrous drug delivery systems for wound therapy.
Electrospinning is an effective method in preparing polymeric nanofibrous drug delivery systems (DDSs) for topical wound healing and skin burn therapy applications. The aim of the present study was to investigate a new synthetic graft copolymer (Soluplus) as a hydrophilic carrier polymer in electrospinning of nanofibrous DDSs. Soluplus (polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (PCL-PVAc-PEG)) was applied in the nonwoven nanomats loaded with piroxicam (PRX) as a poorly water-soluble drug. Raman spectroscopy, X-ray powder diffraction, differential scanning calorimetry, and scanning electron microscopy (SEM) were used in the physical characterization of nanofibrous DDSs. According to the SEM results, the drug-loaded PCL-PVAc-PEG nanofibers were circular in cross-section with an average diameter ranging from 500?nm up to 2? Ąm. Electrospinning stabilized the amorphous state of PRX. In addition, consistent and sustained-release profile was achieved with the present nanofibrous DDSs at the physiologically relevant temperature and pH applicable in wound healing therapy. In conclusion, electrospinning can be used to prepare nanofibrous DDSs of PCL-PVAc-PEG graft copolymer (Soluplus) and to stabilize the amorphous state of a poorly water-soluble PRX. The use of this synthetic graft copolymer can open new options to formulate nanofibrous DDSs for wound healing. PMID:24575414
Paaver, Urve; Tamm, Ingrid; Laidmõe, Ivo; Lust, Andres; Kirsimõe, Kalle; Veski, Peep; Kogermann, Karin; Heinõmõki, Jyrki
Radical addition of methyldichlorosilane to vinyl acetate
The GC-MS method was used to identify the addition products of methyldichlorosilane to vinyl acetate. Radiation-induced addition of methyldichlorosilane to vinyl acetate produces 2-methyldichlorosilylethyl ethyl ether. The reaction follows a radical-chain mechanism. The ratio of the rate constants of methyldichlorosilyl radical addition to C=C and C=O to vinyl acetate amounts to 0.4▒0.1 (303 K).
Yu. M. Lugovoi; N. P. Tarasova; G. Bourgeois; N. V. Bryantseva; V. V. Kostikov; C. Filliatre; A. G. Shostenko
Graft polymerization of vinyl acetate onto silica
The free-radical graft polymerization of vi- nyl acetate onto nonporous silica particles was studied ex- perimentally. The grafting procedure consisted of surface activation with vinyltrimethoxysilane, followed by free-rad- ical graft polymerization of vinyl acetate in ethyl acetate with 2,2-azobis(2,4-dimethylpentanenitrile) initiator. Initial monomer concentration was varied from 10 to 40% by vol- ume and the reaction was spanned from 50 to
Van Nguyen; Wayne Yoshida; Yoram Cohen
[Synthesis of ethriolophospholipids of acetal type].
New analogues of acetal-type phospholipids were obtained on the basis of ethriol (2-hydroxymethyl-2-ethyl-1,3-propanediol). The starting triol originally was condensed with decanal or dodecanal to form acetals, which were then phosphorylated with tetraethyldiamidophosphorous acid chloride. The amidophosphites were further oxidized with iodosobenzene or sulfurized to the corresponding acetal-type phospholipids and their thio analogues. PMID:17042275
Savin, G A
Oxidative reaction of oxindole-3-acetic acids.
The oxindole-3-acetic acids, oxidative metabolites of indole-3-acetic acid, were isolated from a byproduct of a corn starch manufacturing plant, and were further converted to the 3-hydroxyl derivatives in the presence of metal ion. The mechanical study was followed by a chemical analysis including other byproducts, and suggested the presence of an intermediate that had a radical at the C-3 position of oxindole-3-acetic acids. PMID:14519969
Niwa, Toshio; Ishii, Sayuri; Hiramatsu, Atsushi; Osawa, Toshihiko
Glucoamylase, invertase, and cellulase were entrapped within poly(vinyl alcohol) (PVA) membrane cross-linked by means of irradiation of ultraviolet light. The conditions for immobilization of glucoamylase were examined with respect to enzyme concentration in PVA, sensitizer (sodium benzoate) concentration in PVA, irradiation time, and membrane thickness. Various characteristics of immobilized glucoamylase were evaluated. Among them, the pH activity curve for the immobilized enzyme was superior to that for the native one, and thermal stability was improved by immobilization with bovine albumin. The apparent Km was larger for immobilized glucoamylase than for the native one, while Vmax was smaller for the immobilized enzyme. Also, the apparent Km appeared to be affected by the molecular size of the substrate. Further, immobilized invertase and cellulase showed good stabilities in repeating usage. 9 references.
Imai, K.; Shiomi, T.; Uchida, K.; Miya, M.
Pulmonary effects of polyvinyl chloride dust exposure on compounding workers.
Spirometry, chest radiography, environmental measurements, and a questionnaire on respiratory symptoms were used to evaluate the effects of exposure to polyvinyl chloride (PVC) dust on 171 Chinese and Malay PVC compounding workers in comparison with an unexposed reference group. Workers with high cumulative PVC dust exposure had a lower forced expiratory volume in 1 s and forced vital capacity, and a higher prevalence of radiological profusion of small opacities. Wheezing or chest tightness was also significantly more frequent in this group. Unlike previous studies, the PVC compounding workers in this study were exposed to only negligible amounts, if any, of vinyl chloride monomer or thermal degradation products of PVC such as hydrogen chloride, phosgene, or chlorine. The conclusion was drawn that a low grade of pneumoconiosis and a small degree of lung function impairment is associated with PVC dust exposure. Reversible airways obstruction is also likely and warrants further investigation. PMID:2047807
Ng, T P; Lee, H S; Low, Y M; Phoon, W H; Ng, Y L
Lung function in workers exposed to polyvinyl chloride dust.
Several reported studies on the effects of polyvinyl chloride (PVC) dust in animals and man have been conflicting. The present study of the ventilatory function of 509 male workers exposed to PVC dust was made in 1977. Altogether 104 men exposed to PVC dust only, 112 men exposed to non-chlorinated solvents only, and 293 men exposed to a mixture of both completed the MRC questionnaire on respiratory function and performed simple spirometric tests (forced expiratory volume in one second and forced vital capacity). No differences were found between the three groups after allowance was made for age, height, and smoking. When exposure and smoking effects were considered separately, the latter was shown to be the dominant cause of reduced lung function. In this study work with PVC dust has not produced deleterious effects on ventilatory function. PMID:7426465
Chivers, C P; Lawrence-Jones, C; Paddle, G M
Electroactive nonionic poly(vinyl alcohol) gel actuator
A fast (0.8sec), large (>10%) and reversible deformation of Poly(vinyl alcohol) gel (PVA) swollen with dimethyl sulfoxide (DMSO) upon electric field was realized, and the maximum observed strain reached quite high 27% (DP2100). St-PVA gels were found to exhibit more stable and reversible deformation than at-PVA gels. Furthermore, we have studied the macroscopic structure of PVA/DMSO gels and its influence on their strain exhibition. Four differently structured PVA/DMSO gels, monolayer, circular, triple-layered and porous, were prepared. Monolayer gel exhibited the highly reproducible strain behavior. The mechanism of electric actuation of PVA/DMSO gel is proposed. Then a design of gel mechanical switch is shown, which exhibited the fast response to the electric field with a large, stable and reversible stretching deformation.
Popovic, Suzana; Xu, Chunye; Tamagawa, Hirohisa; Taya, Minoru
Speciation of organotins in poly(vinyl chloride) products.
Extraction studies on butyl- and octyltins were conducted with three poly(vinyl chloride) (PVC) product types: clear food container, rigid pipe and flexible membrane. Three solvents, tetrahydrofuran, xylene and methylene chloride were evaluated for extraction efficiency. Methylene chloride extracted more than 97% of the total extractable organotin in two extractions and resulted in the highest recoveries of analytes from all three PVC products. Method detection limits ranged from 0.3 to 0.9 microgram alkyltin/g PVC. The mean precision of the method is 6.8% relative standard deviation. Food industry PVC product samples contained between < 0.8 and 8751 micrograms/g octyltins and < 0.3 and 4.7 micrograms/g butyltins. Butyltins (< 0.9-5985 micrograms/g) were detected in potable water pipe samples. Pipe used in industrial applications contained both butyl- (13-1501 micrograms/g) and octyltins (701-3033 micrograms/g). PMID:8224321
Forsyth, D S; Dabeka, R; Sun, W F; Dalglish, K
Polyvinyl pirrolidone-mediated phase transitions in metastable nanocrystalline cobalt
Actual and potential applications of metallic cobalt rely on its crystal size- and phase-dependent magnetic properties. On this basis, the present work addresses the synthesis and characterization of nanocrystalline cobalt particles produced through a modified polyol-based approach, which is conducive to the formation of epsilon (?-Co) or hcp-Co phases. Metastable V-Co could be converted into hcp-Co by controlled additions of polyvinyl pirrolidone (PVP) in trimethylene-glycol. XRD evidenced the progressive conversion of the V-Co phase into the hcp-Co phase, as the PVP/Co mole ratio increased from 0 to 11. Magnetic measurements confirmed the strong influence of synthesis conditions on crystal structure and hence, on magnetic properties; the coercivity of the products varied from 134 Oe for V-Co to 752 Oe for the hcp-Co. These values agreed with the soft magnetic nature of epsilon and hard magnetic character of hexagonal phases of cobalt.
Osorio-Cantillo, C.; Perales-Perez, O.; Guinel, M. Jf.
Friction loss in straight pipes of unplasticized polyvinyl chloride.
In order to design proper ductwork for a local exhaust system, airflow characteristics were investigated in straight pipes of unplasticized polyvinyl chloride (PVC). A linear decrease in static pressure was observed downstream at points from the opening of the VU pipes (JIS K 6741) located at distances greater than 10 times the pipe diameter, for velocities ranging between 10.18-36.91 m/s. Roughness inside pipes with small diameters was found to be 0.0042-0.0056 mm and the friction factor was calculated on the basis of Colebrook's equation for an airflow transition zone. An extended friction chart was then constructed on the basis of the roughness value and the friction factor. This chart can be applied when designing a local exhaust system with the ducts of diameters ranging from 40 to 900 mm. The friction loss of the PVC pipe was found to be approximately 2/3 of that of a galvanized steel pipe. PMID:8768669
Iwasaki, T; Ojima, J
Biodegradable thermoplastic composites based on polyvinyl alcohol and algae.
Algae constitute a largely available, low value material from renewable resources of marine origin to be used for the production of eco-compatible composites. Fibers of the green alga Ulva armoricana from the French coast were positively evaluated for the production of composites with a hydrophilic, eco-compatible polymer, such as poly(vinyl alcohol) (PVA) as continuous matrix by casting of aqueous suspensions and compression molding. PVA, Ulva, and starch were also successfully processed by the melt in the presence of glycerol. Positive results were obtained for film-forming properties and mechanical characteristics also with limited amounts of PVA (40%) attesting for Ulva suitability to be introduced in composites (up to 30%). Degradation in soil of Ulva and an Ulva-based composites outlined a rapid mineralization of Ulva in the selected medium (over 80% in 100 days) while the composite samples underwent a mineralization rate affected by the different component propensity to degradation. PMID:18257530
Chiellini, Emo; Cinelli, Patrizia; Ilieva, Vassilka I; Martera, Martina
Vitrification of Polyvinyl Chloride Waste from Korean Nuclear Power Plants
Vitrification is considered as an economical and safe treatment technology for low-level radioactive waste (LLW) generated from nuclear power plants (NPPs). Korea is in the process of preparing for its first ever vitrification plant to handle LLW from its NPPs. Polyvinyl chloride (PVC) has the largest volume of dry active wastes and is the main waste stream to treat. Glass formulation development for PVC waste is the focus of study. The minimum additive waste stabilization approach has been utilized in vitrification. It was found that glasses can incorporate a high content of PVC ash (up to 50 wt%), which results in a large volume reduction. A glass frit, KEP-A, was developed to vitrify PVC waste after the optimization of waste loading, melt viscosity, melting temperature, and chemical durability. The KEP-A could satisfactorily vitrify PVC with a waste loading of 30 to 50 wt%. The PVC-frit was tolerant of variations in waste composition.
Sheng, Jiawei [Kyoto University (Japan); Choi, Kwansik [Nuclear Environment Technology Institute (Korea, Republic of); Yang, Kyung-Hwa [Nuclear Environment Technology Institute (Korea, Republic of); Lee, Myung-Chan [Nuclear Environment Technology Institute (Korea, Republic of); Song, Myung-Jae [Nuclear Environment Technology Institute (Korea, Republic of)
ZnS-polyvinyl pyrrolidone nanocomposite was prepared by a simple wet-chemical route. TEM and x-ray diffraction confirmed the formation of nanometre size ZnS particles within the polymer matrix. The average particle size was between 10 and 12 nm. The third-order susceptibility ?(3) of the nanocomposite suspension was measured by employing a single beam z-scan setup with 38 ps laser pulses at 532 nm. The results show that the ZnS nanoparticle exhibits saturable absorption and large third-order susceptibility ?(3) (10-9 esu). The difference in optical nonlinearity between the ZnS/PVP suspension and another ZnS nanocomposite was discussed.
Wang, Cunxiu; Guan, Liusan; Mao, Yanli; Gu, Yuzong; Liu, Junhui; Fu, Shishu; Xu, Qinghai
Sulfonated polyvinyl chloride fibers for cation-exchange microextraction.
Polyvinyl chloride (PVC) fiber was derivatized by concentrated sulfuric acid to yield sulfonated PVC (PVC-SO3H). The PVC-SO3H fiber had dual properties as a sorbent, based on cation-exchange and hydrophobicity. In the present study, the novel fiber was used directly as an individual device for extraction purposes in the cation-exchange microextraction of anaesthetics, followed by high-performance liquid chromatography-UV analysis. The results demonstrated that this PVC-SO3H fiber-based microextraction afforded convenient operation and cost-effective application to basic analytes. The limits of detection for four anaesthetics ranged from 1.2 to 6.0 ng/mL. No carryover (because of its disposable usage), and no loss of sorbent phase (which normally occurs in stir-bar sorptive extraction) during extraction were observed. PMID:19682696
Xu, Li; Lee, Hian Kee
Creatininium 2-chloro-acetate
In the title compound (systematic name: 2-amino-1-methyl-4-oxo-4,5-dihydro-1H-imidazol-3-ium 2-chloroŁacetate), C4H8N3O+ĘC2H2ClO2 ?, the molŁecular aggregations are stabilŁized through classical (NŚH?O) and non-classical (CŚH?O and CŚH?N) hydrogen-bonding interŁactions. The cations are linked to the anions, forming ion pairs through two NŚH?O bonds that produce characteristic R 2 2(8) ring motifs. These cation¢anion pairs are connected through another NŚH?O hydrogen bond, leading to an R 4 2(8) ring motif. Further weak CŚH?N interŁactions link the molŁecules along the a axis, while other CŚH?O interŁactions generate zigzag chains extending along b.
Ali, A. Jahubar; Athimoolam, S.; Bahadur, S. Asath
Covalently attached, silver-doped poly(vinyl alcohol) hydrogel films on poly(l-lactic acid).
Covalently attached, soft poly(vinyl alcohol) (PVA) hydrogel films containing silver particles were prepared on solid biodegradable poly(l-lactic acid) (PLLA) samples by a multistep procedure involving oxygen plasma treatment, UV-initiated graft polymerization, and chemical grafting methods. The modification steps were followed and verified using attenuated total reflection infrared spectroscopy and X-ray photoelectron spectroscopy. 2-Hydroxyethyl methacrylate (HEMA) was graft polymerized from the surface of oxygen plasma-treated PLLA film samples and the alcohol functionality in the grafted polyHEMA chains was oxidized using pyridinium dichromate to obtain an aldehyde-rich surface. PVA was then grafted onto this surface using acid catalysis (acetal formation). The "freeze/thaw method" was used to form a PVA hydrogel layer that incorporated the covalently grafted PVA chains in the physically cross-linked gel. This composite film (PLLA-PVA(gel)) was doped with silver ions, which were reduced to silver using NaBH(4). Scanning electron microscopy of cross sections of PLLA-PVA(gel) indicates robust attachment of the PVA hydrogel layer to the PLLA film. PLLA-PVA(gel/Ag(0)) film samples exhibit both antibacterial and reduced cell adhesion properties due to the antibacterial properties of silver nanoparticles and high water content, respectively. This method provides a route to mechanically sound biodegradable materials with tunable soft material surface properties. Potential applications in tissue engineering and biomedical devices are envisioned. PMID:20307097
Zan, Xingjie; Kozlov, Mikhail; McCarthy, Thomas J; Su, Zhaohui
(Acetoxy)(2-methylphenyl)methyl acetate
In the title compound, C12H14O4, the two acetŁoxy groups are inclined by 57.92?(5)░ and 62.71?(6)░ to the benzene ring. An interŁmolecular CŚH?O interŁaction involving the two acetŁoxy groups generates a centrosymmetric dimer via an R 2 2(16) ring motif.
Kanchanadevi, J.; Anbalagan, G.; Saravanan, V.; Mohanakrishnan, A. K.; Manivannan, V.
Biodegradable Plastics Based on Cellulose Acetate
It is generally known that secondary cellulose acetate (with 53 to 56% acetyl groups) is suitable for thermoplastic processing. With appropriate plasticizers a plastic material is obtained which excels in transparency and pleasant texture, and it is therefore often used for tool handles, combs, spectacle frames, and the like. In principle, cellulose acetate with such a degree of substitution is
Alexander Ach
Heating of dried, acetate-containing solids together with oxalic acid dihydrate conveniently releases acetic acid for purification by gas chromatography. For determination of the carbon-isotopic composition of total acetate, the acetate-containing zone of the chromatographic effluent can be routed directly to a combustion furnace coupled to a vacuum system allowing recovery, purification, and packaging of CO{sub 2} for mass-spectrometric analysis. For analysis of methyl carbon, acetic acid can be cryogenically trapped from the chromatographic effluent, then transferred to a tube containing excess NaOH. The tube is evacuated, sealed, and heated to 500{degree}C to produce methane by pyrolysis of sodium acetate. Subsequent combustion of the methane allows determination of the {sup 13}C content at the methyl position in the parent acetate. With typical blanks, the standard deviation of single analyses is less than 0.4{per thousand} for acetate samples larger than 5 {mu}mol. A full treatment of uncertainties is outlined.
Gelwicks, J.T. (Merck and Co., Inc., Rahway, NJ (USA)); Hayes, J.M. (Indiana Univ., Bloomington (USA))
Modification of Poly(vinyl butyral) Coatings Using Bis-silanes (Postprint).
A commercially available poly(vinyl butyral) (PVB) coating was modified using a combination of 1-10 wt.% bis(trimethoxysilylethyl)benzene and dibutyltin dilaurate as the hydrolysis catalyst. Results of attenuated total reflectance (ATR)-FTIR analysis indi...
M. V. Henley T. L. Metroke
Worker Exposure to Vinyl Chloride in Vinyl Chloride and Polyvinyl Chloride Production and Fabrication.
In assessment of worker exposure to vinyl-chloride (75014) (VC) and polyvinyl-chloride (9002862) (PVC) was reported. Toxicological data were presented, including acute and chronic animal and human studies, as well as reported worker exposures. Common meth...
J. H. Jones
Growth control of ice crystals by poly(vinyl alcohol) and antifreeze protein in ice slurries
Effect of poly(vinyl alcohol) (PVA) in inhibiting an increase in ice crystal size in isothermal ice slurries was investigated, and then compared with the effect of an antifreeze protein (AFP), NaCl, and three other polymers, namely, poly(ethylene glycol), poly(vinyl pyrrolidone), and poly(acrylic acid). First, ice slurries, in which the initial size distribution of ice crystals was known, were isothermally preserved
Takaaki Inada; Poly Rani Modak
Pseudomonas fluorescens lipase immobilization on polysiloxane¢polyvinyl alcohol composite chemically modified with epichlorohydrin
The technique based on sol¢gel approach was used to generate silica matrices derivatives by hydrolysis of silane compounds. The present work evaluates a hybrid matrix obtained with tetraethoxysilane (TEOS) and polyvinyl alcohol (PVA) on the immobilization yield of lipase from Pseudomonas fluorescens. The resulting polysiloxane¢polyvinyl alcohol (POS¢PVA) matrix combines the property of PVA as a suitable polymer to retain proteins
J. C. Santos; A. V. Paula; G. F. M. Nunes; H. F. de Castro
Hybrid material polyvinyl alcohol-copper oxide and its electrical properties
The hybrid material polyvinyl alcohol-copper oxide was produced by the thermal decomposition of polyvinyl alcohol-copper hydroxide complex compound. It was analyzed by means of XRD, UV-VIS, IR, and Raman spectroscopy. It was concluded that the most part of copper oxide has an amorphous structure and consists of -(Cu-O) n - chains. The electrical properties of this material were investigated at direct and alternating current in 80-375 K temperature range.
Prosanov, I. Yu.; Bulina, N. V.; Chesalov, Yu. A.
Poly(vinyl alcohol) Membranes Having an Integrally Skinned Asymmetric Structure
Poly(vinyl alcohol) membranes, having integrally skinned asymmetric structures, were prepared by using 2-propanol and cosolvent composed of N-methyl-2-pyrrolidone and water, by phase inversion processes. In this work, the effects of cosolvent on the formation of integrally skinned structure of the asymmetric poly(vinyl alcohol) membranes were investigated and discussed from the morphological point of view. Experimental result indicated that the resulting
Sang-Gyun Kim; Kew-Ho Lee
Poly(vinyl chloride) (PVC) hollow fiber ultrafiltration membranes prepared from PVC\\/additives\\/solvent
Using poly(vinyl pyrrolidone) (PVP 40,000) or poly(ethylene glycol) (PEG) with different molecular weights (PEG 600, PEG 800, PEG 1000) as additives and N,N-dimethylacetamide (DMAc) as a solvent, asymmetric poly(vinyl chloride) (PVC) hollow fiber ultrafiltration membranes were prepared by phase inversion technique from 14 to 20wt.% solids including PVC and additives. The 95\\/5 DMAc\\/water and pure water were used as the
Jian Xu; Zhen-Liang Xu
Effects of nanoscale dispersion in the dielectric properties of poly(vinyl alcohol)-bentonite nanocomposites
We investigate the effects of clay proportion and nanoscale dispersion in the dielectric response of poly(vinyl alcohol)-bentonite nanocomposites. The dielectric study was performed using the thermally stimulated depolarization current technique, covering the temperature range of the secondary and high-temperature relaxation processes. Important changes in the secondary relaxations are observed at low clay contents in comparison with neat poly(vinyl alcohol) (PVA).
MarĒa C. Hernßndez; N. Sußrez; Luis A. MartĒnez; Josķ L. Feijoo; Salvador Lo M¾naco; Norkys Salazar
Dielectric dispersion study of coexisting phases of aqueous polymeric solution: Poly(vinyl alcohol) + poly(vinyl pyrrolidone) two-phase systems
The complex dielectric constant ??(?)=???j??, electric modulus M?(?)=M?+jM?, impedance Z?(?)=Z??jZ? and ac conductivity dispersion behaviour of 5, 10 and 15wt% concentration aqueous solutions of poly(vinyl alcohol) (PVA) (14?000 and 77?000gmol?1) and poly(vinyl pyrrolidone) (PVP) (24?000, 40?000 and 360?000gmol?1) and their binary mixtures were investigated in the frequency range 20Hz to 1MHz at 25░C. Analysis of dielectric constant values confirms that
R. J. Sengwa; Sonu Sankhla
Emulsion polymerization of vinyl acetate: safe optimization of a hazardous complex process.
Fast and exothermic discontinuous emulsion polymerization processes are particularly difficult to optimize from both safety and productivity point of view because of the occurrence of side undesired reactions (e.g. chain transfer to monomer, backbiting, propagation of tertiary radicals, termination by disproportion, etc.) and the hazards of boiling phenomena and stable foam formation under atmospheric pressure. Moreover, the relevant number of loading, heating and cooling steps, required before starting the monomer addition (that is, the desired reaction), makes a strict product quality reproducibility very difficult to obtain. Under these operating conditions, it is necessary to employ a suitable combined theoretical and experimental procedure able to detect the optimum process dosing time at both the laboratory and the industrial scale. In this work, it is shown how to use the topological criterion theory together with proper adiabatic calorimeter and RC1 experimental data to safely optimize the synthesis of polyvinyl acetate through the radical emulsion polymerization of vinyl acetate by the means of an indirectly cooled isoperibolic semibatch reactor. PMID:21632179
Copelli, S; Derudi, M; Sempere, J; Serra, E; Lunghi, A; Pasturenzi, C; Rota, R
Ulipristal acetate in emergency contraception.
Despite the widespread availability of highly effective methods of contraception, unintended pregnancy is common. Unplanned pregnancies have been linked to a range of health, social and economic consequences. Emergency contraception reduces risk of pregnancy after unprotected intercourse, and represents an opportunity to decrease number of unplanned pregnancies and abortions. Emergency contraception pills (ECP) prevent pregnancy by delaying or inhibiting ovulation, without interfering with post fertilization events. If pregnancy has already occurred, ECPs will not be effective, therefore ECPs are not abortificants. Ulipristal acetate (17alpha-acetoxy-11beta-(4N-N,N-dymethilaminophenyl)-19-norpregna--4,9-diene-3,20-dione) is the first drug that was specifically developed and licensed for use as an emergency contraceptive. It is an orally active, synthetic, selective progesterone modulator that acts by binding with high affinity to the human progesterone receptor where it has both antagonist and partial agonist effects. It is a new molecular entity and the first compound in a new pharmacological class defined by the pristal stem. Up on the superior clinical efficacy evidence, UPA has been quickly recognized as the most effective emergency contraceptive pill, and recently recommended as the first prescription choice for all women regardless of the age and timing after intercourse. This article provides literature review of UPA and its role in emergency contraception. PMID:24851646
Goldstajn, Marina Sprem; Baldani, Dinka Pavici?; Skrgati?, Lana; Radakovi?, Branko; Vrbi?, Hrvoje; Cani?, Tomislav
Application of lipase immobilized on the biocompatible ternary blend polymer matrix for synthesis of citronellyl acetate in non-aqueous media: kinetic modelling study.
This work reports the use of new support for immobilization of lipase Burkholderia cepacia (BCL) matrix made up of polylactic acid (PLA), chitosan (CH), and polyvinyl alcohol (PVA). Initially lipase from various microbial sources and immobilization support composition was screened to obtain a robust biocatalyst. Among various biocatalysts preparation, the PLA:PVA:CH:BCL (1:6:1:2) was worked as a robust biocatalyst for the citronellyl acetate synthesis. Various reaction parameters were studied in detail to obtain the suitable reaction conditions for model citronellyl acetate synthesis reaction. Various kinetic parameters such as r(max), K(i(citronellol)), K(m(citronellol)), K(m(vinyl acetate)) were determined using non-linear regression analysis for the ternary complex as well as bi-bi ping-pong mechanism. The experimental results and kinetic study showed that citronellyl acetate synthesis catalyzed by immobilized lipase BCL followed the ternary complex mechanism with inhibition by alcohol (citronellol). The energy of activation for citronellyl acetate synthesis was found to be lower for immobilized lipase (8.9 kcal/mol) than aggregated lipase (14.8 kcal/mol) enzyme. The developed biocatalyst showed four to fivefold higher catalytic activity and excellent recyclability (up to six cycles) than the aggregated lipase. PMID:24629263
Badgujar, Kirtikumar C; Bhanage, Bhalchandra M
Doped with Sodium Acetate and Metallic Sodium
We have investigated the thermoelectric properties of p-type Na-doped Mg2 Si0.25Sn0.75 solid solutions prepared by liquid-solid reaction and hot-pressing methods. Na was introduced into Mg2Si0.25Sn0.75 by using either sodium acetate (CH3COONa) or metallic sodium (2 N). The samples doped with sodium acetate consisted of phases with antifluorite structure and a small amount of MgO as revealed by x-ray diffraction, whereas the sample doped with metallic sodium contained the Sn, MgO, and Mg2SiSn phases. The hole concentrations of Mg1.975Na0.025Si0.25Sn0.75 doped by sodium acetate and metallic sodium were 1.84 ū 1025 m-3 and 1.22 ū 1025 m-3, respectively, resulting in resistivities of 4.96 ū 10-5 ? m (sodium acetate) and 1.09 ū 10-5 ? m (metallic sodium). The Seebeck coefficients were 198 ?V K-1 (sodium acetate) and 241 ?V K-1 (metallic sodium). The figures of merit for Mg1.975Na0.025Si0.25Sn0.75 were 0.40 ū 10-3 K-1 (sodium acetate) and 0.25 ū 10-3 K-1 (metallic sodium) at 400 K. Thus, sodium acetate is a suitable Na dopant for Mg2Si1- x Sn x .
Tada, Satoki; Isoda, Yukihiro; Udono, Haruhiko; Fujiu, Hirofumi; Kumagai, Shunji; Shinohara, Yoshikazu
36 CFR 1232.24 - Unstable cellulose-acetate film.
...2009-07-01 2009-07-01 false Unstable cellulose-acetate film. 1232.24 Section 1232...Audiovisual Records Management ┬¦ 1232.24 Unstable cellulose-acetate film. Cellulose-acetate film, also known as safety...
21 CFR 172.833 - Sucrose acetate isobutyrate (SAIB).
... 2009-04-01 2009-04-01 false Sucrose acetate isobutyrate (SAIB). 172.833...CONSUMPTION Multipurpose Additives ┬¦ 172.833 Sucrose acetate isobutyrate (SAIB). Sucrose acetate isobutyrate may be safely used in...
...3 2010-01-01 2009-04-01 true Sucrose acetate isobutyrate (SAIB). 172.833...CONSUMPTION Multipurpose Additives ┬¦ 172.833 Sucrose acetate isobutyrate (SAIB). Sucrose acetate isobutyrate may be safely used in...
40 CFR 414.40 - Applicability; description of the thermoplastic resins subcategory.
...Resins Polyvinyl Acetate *Polyvinyl AcetateŌPVC Copolymers *Polyvinyl Acetate Copolymers ...*Polyvinylidene-Vinyl Chloride Resins *PVC Copolymers, Acrylates (Latex) *PVC Copolymers, Ethylene-Vinyl Chloride...
The effect of desoxycorticosterone acetate (DCA) on the granulation tissue of healing and healed linear laparotomy wounds was studied in young adult male guinea pigs maintained on a complete diet and on a known intake of ascorbic acid. DCA induces the production of an excessive amount of granulation tissue, as evidenced by a relatively great number of fibroblasts and by a larger amount of ground substance. This effect was accompanied by a slight to moderate lag in the maturation process of both cellular and intercellular elements. These changes were observed when DCA administration was begun 5 days prior to operation, but were less obvious or absent if DCA was injected, beginning on the 5th or 10th postoperative day. The results indicate that the action of DCA on immature, proliferating connective tissue is marked, and is considerably less or absent when connective tissue elements have reached partial or almost complete maturity. The effect of DCA on connective tissue does not appear to rest on the basis of an altered nutritional status. Chemical and histochemical studies of the adrenals suggest that the action of DCA on connective tissue is probably mediated through a disturbance of adrenocortical function, namely an imbalance between hormones of the zona glomerulosa (excess of DCA) and those of the zona fasciculata (deficiency of glucocorticoids). The presence of changes in granulation tissue and the lack of them in mature resting connective tissue of DCA-treated guinea pigs confirm the view that a profound difference in the response mechanism exists between resting and actively proliferating connective tissue.
Pirani, Conrad L.; Stepto, Robert C.; Sutherland, Kenneth
The pharmacology of nomegestrol acetate.
Nomegestrol acetate (NOMAC) is a 19-norprogesterone derivative with high biological activity at the progesterone receptor, a weak anti-androgenic effect, but with no binding to estrogen, glucocorticoid or mineralocorticoid receptors. At dosages of 1.5mg/day or more, NOMAC effectively suppresses gonadotropic activity and ovulation in women of reproductive age. Hemostasis, lipids and carbohydrate metabolism remain largely unchanged. In normal and cancerous human breast cells, NOMAC has shown favorable effects on estrogen metabolism. Like natural progesterone (but in contrast to some other synthetic progestogens), it does not appear stimulate the proliferation of cancerous breast cells. While there has been some experience of the use of NOMAC in combination with estrogens as a hormone replacement therapy, most of the data on the compound are reported in the context of its inclusion as a component of a new contraceptive pill comprising 2.5mg NOMAC combined with 1.5mg estradiol. Because of its strong endometrial efficacy, and due to its high antigonadotropic activity and long elimination half-life (about 50h), the contraceptive efficacy of the new pill is maintained even when dosages are missed. Furthermore, for the first time with a monophasic 24/4 regimen containing estradiol, cyclical stability can be achieved comparable with that obtained using pills containing ethinyl estradiol and progestogens like levonorgestrel or drospirenone. The addition of NOMAC to estradiol means that the beneficial effects of estrogen are not lost, which is of especial importance in relation to the cardiovascular system. On the basis both of its pharmacology and of studies performed during the development of the NOMAC/estradiol pill, involving some 4000 women in total, good long-term tolerability can be expected for NOMAC, although its safety profile is still to be fully ascertained, as the clinical endpoint studies are yet to be completed. PMID:22364709
Ruan, Xiangyan; Seeger, Harald; Mueck, Alfred O
Correlation between acetic acid resistance and characteristics of PQQ-dependent ADH in acetic acid bacteria.
In this study, we compared the growth properties and molecular characteristics of pyrroloquinoline quinone (PQQ)-dependent alcohol dehydrogenase (ADH) among highly acetic acid-resistant strains of acetic acid bacteria. Gluconacetobacter europaeus exhibited the highest resistance to acetic acid (10%), whereas Gluconacetobacter intermedius and Acetobacter pasteurianus resisted up to 6% of acetic acid. In media with different concentrations of acetic acid, the maximal acetic acid production rate of Ga. europaeus slowly increased, but specific growth rates decreased concomitant with increased concentration of acetic acid in medium. The lag phase of A. pasteurianus was twice and four times longer in comparison to the lag phases of Ga. europaeus and Ga. intermedius, respectively. PQQ-dependent ADH activity was twice as high in Ga. europaeus and Ga. intermedius as in A. pasteurinus. The purified enzymes showed almost the same specific activity to each other, but in the presence of acetic acid, the enzyme activity decreased faster in A. pasteurianus and Ga. intermedius than in Ga. europaeus. These results suggest that high ADH activity in the Ga. europaeus cells and high acetic acid stability of the purified enzyme represent two of the unique features that enable this species to grow and stay metabolically active at extremely high concentrations of acetic acid. PMID:16133326
Trcek, Janja; Toyama, Hirohide; Czuba, Jerzy; Misiewicz, Anna; Matsushita, Kazunobu
Poly(vinyl alcohol) gels as photoacoustic breast phantoms revisited
A popular phantom in photoacoustic imaging is poly(vinyl alcohol) (PVA) hydrogel fabricated by freezing and thawing (F-T) aqueous solutions of PVA. The material possesses acoustic and optical properties similar to those of tissue. Earlier work characterized PVA gels in small test specimens where temperature distributions during F-T are relatively homogeneous. In this work, in breast-sized samples we observed substantial temperature differences between the shallow regions and the interior during the F-T procedure. We investigated whether spatial variations were also present in the acoustic and optical properties. The speed of sound, acoustic attenuation, and optical reduced scattering coefficients were measured on specimens sampled at various locations in a large phantom. In general, the properties matched values quoted for breast tissue. But while acoustic properties were relatively homogeneous, the reduced scattering was substantially different at the surface compared with the interior. We correlated these variations with gel microstructure inspected using scanning electron microscopy. Interestingly, the phantom's reduced scattering spatial distribution matches the optical properties of the standard two-layer breast model used in x ray dosimetry. We conclude that large PVA samples prepared using the standard recipe make excellent breast tissue phantoms.
Xia, Wenfeng; Piras, Daniele; Heijblom, Michelle; Steenbergen, Wiendelt; van Leeuwen, Ton G.; Manohar, Srirang
Preparation and flammability of poly(vinyl alcohol) composite aerogels.
Poly(vinyl alcohol) (PVOH)-based aerogel composites with nanoscale silica, halloysite, montmorillonite (MMT), and laponite were prepared via a freeze-drying method. The PVOH/MMT and PVOH/laponite composites exhibit higher compressive moduli than the PVOH/SiO2 or PVOH/halloysite samples. Layered microstructures were observed for the samples except with PVOH/laponite, which showed irregular network morphologies. Thermogravimetric analysis of the aerogel samples showed increased thermal stability with the addition of nanofillers. The heat release measured by cone calorimetry, smoke release, and carbon monoxide production of the aerogel composites are all significantly decreased with the addition of nanofillers; these values are much lower than those for commercial expanded polystyrene foam. The fillers did not lead to obvious increases in the limiting oxygen index values, and the corresponding time to ignition values decrease. The ability to adjust the nanofiller levels in these foamlike aerogel composites allows for specific tuning of these products for fire safety. PMID:24731187
Chen, Hong-Bing; Wang, Yu-Zhong; Schiraldi, David A
Electrospun chitosan/polyvinyl alcohol nanofibre mats for wound healing.
Chitosan (CS) aqueous salt blended with polyvinyl alcohol (PVA) nanofibre mats was prepared by electrospinning. CS was dissolved with hydroxybenzotriazole (HOBt), thiamine pyrophosphate (TPP) and ethylenediaminetetraacetic acid (EDTA) in distilled water without the use of toxic or hazardous solvents. The CS aqueous salts were blended with PVA at different weight ratios, and the effect of the solution ratios was investigated. The morphologies and mechanical and swelling properties of the generated fibres were analysed. Indirect cytotoxicity studies indicated that the CS/PVA nanofibre mats were non-toxic to normal human fibroblast cells. The CS-HOBt/PVA and CS-EDTA/PVA nanofibre mats demonstrated satisfactory antibacterial activity against both gram-positive and gram-negative bacteria, and an in vivo wound healing test showed that the CS-EDTA/PVA nanofibre mats performed better than gauze in decreasing acute wound size during the first week after tissue damage. In conclusion, the biodegradable, biocompatible and antibacterial CS-EDTA/PVA nanofibre mats have potential for use as wound dressing materials. PMID:22925275
Charernsriwilaiwat, Natthan; Rojanarata, Theerasak; Ngawhirunpat, Tanasait; Opanasopit, Praneet
Uncommon photoluminescence behavior of Fe3+ doped polyvinyl alcohol films
In this paper, pure and Fe3+ doped polyvinyl alcohol (PVA) films, using FeCl3, are prepared by a solution casting method. The effect of Fe3+doping on the photoluminescence (PL) behavior of PVA is investigated in the temperature range from 10 to 300 K. At 300 K, the PL spectrum of pure PVA is formed by two bands I1and I2. These two bands can be connected with trap states inside the band gap. The PL intensities of I1 and I2 are found to increase with increasing the doping content. The temperature dependence of the PL intensity for neat PVA shows a decrease in the PL intensity with temperature assigned to the phonon diffusion by the photo-created electron¢hole pairs. However, the PL studies of some doped samples containing an important amount of iron reveal an uncommon behavior of their PL intensity which rises with temperature. Two suggestions are given to explain such a behavior. The first is related to the change in the levels nature inside the bandgap and the second is correlated to the (I1¢I2) energy.
Khalifa, N.; Souissi, A.; Attar, I.; Daoudi, M.; Yakoubi, B.; Chtourou, R.
Dielectric breakdown during Cs+ sputtering of polyvinyl chloride
Thin films of insulating polymers are sometimes analyzed by secondary ion mass spectrometry (SIMS) or by X-ray photoelectron spectroscopy (XPS) without the use of an electron gun. In this work, both SIMS and XPS have been used to study the chemical and structural modifications due to the charge effect during Cs+ sputtering of a thin film of polyvinyl chloride (PVC). The kinetic energy distribution study shows that at a small primary fluence ś1015 Cs+ ions/cm2, the dielectric breakdown voltage of the PVC film is reached, i.e. the minimum voltage that causes a portion of an insulator to become electrically conductive. XPS study indicates that the conducting phase created in the PVC film after energetic Cs+ bombardment consists of graphitized carbon and metallic cesium clusters. After the dielectric breakdown of the film, the positive charge, previously accumulated on the surface, is neutralized through the conductive regions, which are created in the insulating film. During Cs+ sputtering of a PVC film, the chemical structure of the analyzed surface is completely modified and some ionic bonds such as CsC and CsCl are also created.
Wahoud, F.; Guillot, J.; Audinot, J. N.; Bertrand, P.; Delcorte, A.; Migeon, H. N.
Density Functional Theory Study of Selective Deacylation of Aromatic Acetate in the Presence of Aliphatic Acetate under Ammonium Acetate Mediated Conditions.
Aromatic acetates can be selectively deprotected in the presence of aliphatic acetates under ammonium acetate mediated condition. B3LYP/6-31++G** level of theory was demonstrated to be successfully used to model the relative reaction rates for deacylation reactions for aliphatic and aromatic ester systems. On the basis of the mechanistic studies, acetate anion is most likely to be the active catalyst for the ester deacylation reactions under ammonium acetate mediated condition. PMID:24956355
Xia, Shijing; Zhang, Haoyu
Acetate Causes Alcohol Hangover Headache in Rats
Background The mechanism of veisalgia cephalgia or hangover headache is unknown. Despite a lack of mechanistic studies, there are a number of theories positing congeners, dehydration, or the ethanol metabolite acetaldehyde as causes of hangover headache. Methods We used a chronic headache model to examine how pure ethanol produces increased sensitivity for nociceptive behaviors in normally hydrated rats. Results Ethanol initially decreased sensitivity to mechanical stimuli on the face (analgesia), followed 4 to 6 hours later by inflammatory pain. Inhibiting alcohol dehydrogenase extended the analgesia whereas inhibiting aldehyde dehydrogenase decreased analgesia. Neither treatment had nociceptive effects. Direct administration of acetate increased nociceptive behaviors suggesting that acetate, not acetaldehyde, accumulation results in hangover-like hypersensitivity in our model. Since adenosine accumulation is a result of acetate formation, we administered an adenosine antagonist that blocked hypersensitivity. Discussion Our study shows that acetate contributes to hangover headache. These findings provide insight into the mechanism of hangover headache and the mechanism of headache induction.
Maxwell, Christina R.; Spangenberg, Rebecca Jay; Hoek, Jan B.; Silberstein, Stephen D.; Oshinsky, Michael L.
Ultrasonic Relaxation in Aqueous Acetic Acid Solutions.
Ultrasonic absorption measurements have been made in aqueous acetic solutions at 15 to 85 MHz using pulse echo and pulse send-receive techniques. A weighted nonlinear regression method has been developed for the computation of the relaxation parameters. A...
L. G. Jackopin E. Yeager
Water dispersible microbicidal cellulose acetate phthalate film
BACKGROUND: Cellulose acetate phthalate (CAP) has been used for several decades in the pharmaceutical industry for enteric film coating of oral tablets and capsules. Micronized CAP, available commercially as \\
A Robert Neurath; Nathan Strick; Yun-Yao Li
Nomegestrol acetate/estradiol: in oral contraception.
Nomegestrol acetate/estradiol is a combined oral contraceptive with approval in many countries. This fixed-dose combination tablet contains nomegestrol acetate, a highly selective progestogen, and estradiol, a natural estrogen. It is the first monophasic combined oral contraceptive to contain estradiol, and is taken in 28-day cycles, consisting of 24 active therapy days with 4 placebo days (i.e. 24/4-day cycles). In two large, 1-year, randomized, open-label, multicentre, phase III trials in healthy adult women (aged 18-50 years), nomegestrol acetate/estradiol was at least as effective as drospirenone/ethinylestradiol as contraceptive therapy, as the pregnancy rates in women aged 18-35 years (primary efficacy population) in terms of the Pearl Index (primary endpoint) were numerically lower with nomegestrol acetate/estradiol, although the between-group difference was not statistically significant. In both trials, nomegestrol acetate/estradiol was given in a 24/4-day cycle, and drospirenone/ethinylestradiol was given in a 21/7-day cycle. The criteria for using condoms in case of forgotten doses were less stringent in the nomegestrol acetate/estradiol group than in the drospirenone/ethinylestradiol group. Nomegestrol acetate/estradiol therapy for up to 1 year was generally well tolerated in healthy adult women, with an acceptable tolerability profile in line with that expected for a combined oral contraceptive. The most commonly reported adverse events were acne and abnormal withdrawal bleeding (most often shorter, lighter or absent periods). Overall, compared with drospirenone/ethinylestradiol, nomegestrol acetate/estradiol appeared to be associated with less favourable acne-related outcomes, and shorter, lighter or absent periods. PMID:22950535
Yang, Lily P H; Plosker, Greg L
Fluorescence quenching of etilefrine by acetate anion
Acid dissociation in the excited state of antihypotensor drug etilefrine [2-(ethylamino1-3-hydroxyphenyl)ethanol] is studied. Fluorescence of etilefrine decreases at pH<7 and is related to phenolic group dissociation. However, intensity of etilefrine fluorescence diminishes as the concentration of the acetate anion increases at pH>7. Analyses of the absorption and fluorescence spectra of aqueous solutions of etilefrine in the presence of acetate anions have been made. Considering the existence of an equilibrium in the excited state the values of 3.47ū10 -9 and 0.216ū10 -9 M -1 s -1 have been obtained for the rate constants for direct and inverse reactions, respectively. Moreover, the lifetime ( ?0'=0.58ū10 -9 s) and quantum yield (0.01) of non-protonated etilefrine have been determined. Our results seem to support the existence of a dynamic quenching process based on a proton transfer mechanism induced by acetate anions. This process could represent a serious inconvenience in analytical fluorimetric techniques taking into account that the acetic acid/acetate pair is commonly used as a buffer. Additional fluorescence quenching by H + ions could be involved in acid aqueous mediums. At high concentrations of acetic acid, a value of 2.98ū10 -9 M -1 s -1 for the bimolecular constant for the quenching by H + has been calculated.
Quintero Osso, B.; Carazo RodrĒguez, F. M.; Morales Domingo, J. J.; Cabeza Gonzßlez, M. C.; Thomas G¾mez, J.
Density data for copolymer systems: butyl acrylate\\/vinyl acetate homo- and copolymerization in ethyl acetate
A study was performed to provide precise density data, badly needed for on-line measurements and control of polymerization reactors, e.g. for densimetry studies. Data was obtained for one copolymer of butyl acrylate\\/vinyl acetate, the homopolymers of vinyl acetate and butyl acrylate, plus the two monomers and ethyl acetate. In addition, the hypothesis of the linear dependence of the density of
I Barudio; G Fķvotte; T. F McKenna
Identification method of synthetic polymers by high-performance liquid chromatography
Polyvinyl chloride (PVC), polyvinyl acetate (PVAc), and their copolymers and blends, polystyrene, poly(methyl, ethyl, and butyl) acrylates and methacrylates were dissolved in tetrahydrofuran (THF), respectively, and the solutions were injected into a column of silica gel having a pore diameter of 30 A and eluted with the mobile phases of THF, chloroform, ethyl acetate, methanol, methylethylketone, acetonitrile and 1,2-dichloroethane (DCE). Some polymers eluted from the column and the rest were retained in the column. The identification of the polymers was not based on the difference in the retention volumes of the polymers, but the elution of the polymers from or the retention in the column were a measure of the identification. This technique was termed as On-Off Elution Method'. Two retention mechanisms were proposed: hydrogen bonding between silica gel and the sample polymers, and the precipitation of polymers in the column. In case of the former, some polymers were retained in the column even though a good solvent to the polymers was used as the mobile phase. When poor solvents to the polymers were used as the mobile phases, the polymers were precipitated in the column, except PVC with DCE. The physical blend of PVC and PVAc could be discriminated from the copolymer having the same composition by this procedure.
Mori, Sadao (Mie Univ., Tsu (Japan))
Direct Detection of the Acetate-forming Activity of the Enzyme Acetate Kinase
Acetate kinase, a member of the acetate and sugar kinase-Hsp70-actin (ASKHA) enzyme superfamily1-5, is responsible for the reversible phosphorylation of acetate to acetyl phosphate utilizing ATP as a substrate. Acetate kinases are ubiquitous in the Bacteria, found in one genus of Archaea, and are also present in microbes of the Eukarya6. The most well characterized acetate kinase is that from the methane-producing archaeon Methanosarcina thermophila7-14. An acetate kinase which can only utilize PPi but not ATP in the acetyl phosphate-forming direction has been isolated from Entamoeba histolytica, the causative agent of amoebic dysentery, and has thus far only been found in this genus15,16. In the direction of acetyl phosphate formation, acetate kinase activity is typically measured using the hydroxamate assay, first described by Lipmann17-20, a coupled assay in which conversion of ATP to ADP is coupled to oxidation of NADH to NAD+ by the enzymes pyruvate kinase and lactate dehydrogenase21,22, or an assay measuring release of inorganic phosphate after reaction of the acetyl phosphate product with hydroxylamine23. Activity in the opposite, acetate-forming direction is measured by coupling ATP formation from ADP to the reduction of NADP+ to NADPH by the enzymes hexokinase and glucose 6-phosphate dehydrogenase24. Here we describe a method for the detection of acetate kinase activity in the direction of acetate formation that does not require coupling enzymes, but is instead based on direct determination of acetyl phosphate consumption. After the enzymatic reaction, remaining acetyl phosphate is converted to a ferric hydroxamate complex that can be measured spectrophotometrically, as for the hydroxamate assay. Thus, unlike the standard coupled assay for this direction that is dependent on the production of ATP from ADP, this direct assay can be used for acetate kinases that produce ATP or PPi.
Fowler, Matthew L.; Ingram-Smith, Cheryl J.; Smith, Kerry S.
Direct detection of the acetate-forming activity of the enzyme acetate kinase.
Acetate kinase, a member of the acetate and sugar kinase-Hsp70-actin (ASKHA) enzyme superfamily, is responsible for the reversible phosphorylation of acetate to acetyl phosphate utilizing ATP as a substrate. Acetate kinases are ubiquitous in the Bacteria, found in one genus of Archaea, and are also present in microbes of the Eukarya. The most well characterized acetate kinase is that from the methane-producing archaeon Methanosarcina thermophila. An acetate kinase which can only utilize PP(i) but not ATP in the acetyl phosphate-forming direction has been isolated from Entamoeba histolytica, the causative agent of amoebic dysentery, and has thus far only been found in this genus. In the direction of acetyl phosphate formation, acetate kinase activity is typically measured using the hydroxamate assay, first described by Lipmann, a coupled assay in which conversion of ATP to ADP is coupled to oxidation of NADH to NAD(+) by the enzymes pyruvate kinase and lactate dehydrogenase, or an assay measuring release of inorganic phosphate after reaction of the acetyl phosphate product with hydroxylamine. Activity in the opposite, acetate-forming direction is measured by coupling ATP formation from ADP to the reduction of NADP(+) to NADPH by the enzymes hexokinase and glucose 6-phosphate dehydrogenase. Here we describe a method for the detection of acetate kinase activity in the direction of acetate formation that does not require coupling enzymes, but is instead based on direct determination of acetyl phosphate consumption. After the enzymatic reaction, remaining acetyl phosphate is converted to a ferric hydroxamate complex that can be measured spectrophotometrically, as for the hydroxamate assay. Thus, unlike the standard coupled assay for this direction that is dependent on the production of ATP from ADP, this direct assay can be used for acetate kinases that produce ATP or PP(i). PMID:22214984
Fowler, Matthew L; Ingram-Smith, Cheryl J; Smith, Kerry S
Friction and wear behaviour of acetal and nylon gears
The current paper will present an extensive investigation of polymer gear (acetal and nylon) friction and wear behaviour. First, a unique test method for polymer gear wear will be described in brief and later used in the extensive investigation of acetal and nylon gear wear. Initial tests were performed using acetal pinions with acetal gears, and nylon pinions with nylon
K. Mao; W. Li; C. J. Hooke; D. Walton
Calcination of calcium acetate and calcium magnesium acetate: effect of the reacting atmosphere
The calcination process of the calcium acetate (CA) and calcium magnesium acetate (CMA) was investigated as a previous step for coal gas desulfurisation during sorbent injection at high temperatures because the excellent results demonstrated by these sorbents as sulfur removal agents both in combustion and gasification processes. As pore structure developed during calcination is one of the most important characteristic
J. Adßnez; L. F. de Diego; F. Garc??a-Labiano
Correlation of vapor - liquid equilibrium data for acetic acid - isopropanol - water - isopropyl acetate mixtures
A correlation procedure for the prediction of vapor - liquid equilibrium of acetic acid - isopropanol - water - isopropyl acetate mixtures has been developed. It is based on the NRTL model for predicting liquid activity coefficients, and on the Hayden-O'Connell second virial coefficients for predicting the vapor phase of systems containing association components. When compared with experimental data the
E. A. Campanella
Tested Demonstrations: Buffer Capacity of Various Acetic Acid-Sodium Acetate Systems: A Lecture Experiment.
ERIC Educational Resources Information Center
Background information and procedures are provided for a lecture experiment which uses indicators to illustrate the concept of differing buffer capacities by titrating acetic acid/sodium acetate buffers with 1.0 molar hydrochloric acid and 1.0 molar sodium hydroxide. A table with data used to plot the titration curve is included. (JN)
Donahue, Craig J.; Panek, Mary G.
Experiments were performed to determine the corrosion rate of lead when exposed to off-gas or degradation products of organic materials used in the model 9975 package.[1] The experiments were completed within the framework of a parametric test matrix with variables of organic configuration, temperature, humidity and the effect of durations of exposure on the corrosion of lead in the 9975 package. The room temperature vulcanizing (RTV) sealant was the most corrosive organic species in the testing, followed by the polyvinyl acetate (PVAc) glue. The Celotex{copyright} material uniquely induced measurable corrosion only in situations with condensed water, and to a much lesser extent than the PVAc glue and RTV. The coupons exhibited faster corrosion at higher temperatures than at room temperatures. There was a particularly pronounced effect of condensed water as the coupons exposed in the cells with condensed water exhibited much higher corrosion rates. In the 9975 package, the PVAc glue was determined to be the most aggressive due to it's proximity in the design. The condition considered most representative of the package conditions is that of the coupon exposed to the Celotex{copyright}/glue organic exposed in the ambient humidity conditions. The corrosion rate of 2 mpy measured in the laboratory experiments for this condition is considered to be a bounding condition to the 9975 package conditions when the laboratory results are extrapolated to actual package conditions, and is recommended as a conservative estimate for package performance calculations.
Subramanian, K
Electrospinning processed nanofibrous TiO(2) membranes for photovoltaic applications.
We have recently fabricated dye-sensitized solar cells (DSSCs) comprising nanofibrous TiO(2) membranes as electrode materials. A thin TiO(2) film was pre-deposited on fluorine doped tin oxide (FTO) coated conducting glass substrate by immersion in TiF(4) aqueous solution to reduce the electron back-transfer from FTO to the electrolyte. The composite polyvinyl acetate (PVac)/titania nanofibrous membranes can be deposited on the pre-deposited thin TiO(2) film coated FTO by electrospinning of a mixture of PVac and titanium isopropoxide in N,N-dimethylformamide (DMF). The nanofibrous TiO(2) membranes were obtained by calcining the electrospun composite nanofibres of PVac/titania as the precursor. Spectral sensitization of the nanofibrous TiO(2) membranes was carried out with a ruthenium (II) complex, cis-dithiocyanate-N,N(')-bis(2,2(')-bipyridyl-4,4(')-dicarboxylic acid) ruthenium (II) dihydrate. The results indicated that the photocurrent and conversion efficiency of electrodes can be increased with the addition of the pre-deposited TiO(2) film and the adhesion treatment using DMF. Additionally, the dye loading, photocurrent, and efficiency of the electrodes were gradually increased by increasing the average thickness of the nanofibrous TiO(2) membranes. The efficiency of the fibrous TiO(2) photoelectrode with the average membrane thickness of 3.9ĀĄm has a maximum value of 4.14%. PMID:21727376
Onozuka, Katsuhiro; Ding, Bin; Tsuge, Yosuke; Naka, Takayuki; Yamazaki, Michiyo; Sugi, Shinichiro; Ohno, Shingo; Yoshikawa, Masato; Shiratori, Seimei
Imaging dielectric relaxation in nanostructured polymers by frequency modulation electrostatic force microscopy
We have developed a method for imaging the temperature-frequency dependence of the dynamics of nanostructured polymer films with spatial resolution. This method provides images with dielectric compositional contrast well decoupled from topography. Using frequency-modulation electrostatic-force-microscopy, we probe the local frequency-dependent (0.1-100 Hz) dielectric response through measurement of the amplitude and phase of the force gradient in response to an oscillating applied electric field. When the phase is imaged at fixed frequency, it reveals the spatial variation in dielectric losses, i.e., the spatial variation in molecular/dipolar dynamics, with 40 nm lateral resolution. This is demonstrated by using as a model system; a phase separated polystyrene/polyvinyl-acetate (PVAc) blend. We show that nanoscale dynamic domains of PVAc are clearly identifiable in phase images as those which light-up in a band of temperature, reflecting the variations in the molecular/dipolar dynamics approaching the glass transition temperature of PVAc.
Riedel, C.; Sweeney, R.; Israeloff, N. E.; Arinero, R.; Schwartz, G. A.; Alegria, A.; Tordjeman, Ph.; Colmenero, J.
Effect of Silica Nanoparticles on Compressive Strength of Leaves-Waste Composite
The utilization of solid-waste, especially leaves-waste is one of interesting research of environmental field. One of them is making a composite using polyvinyl acetate (PVAc) polymer as binder (matrix) and silica nanoparticles as reinforcement (filler) to improve the strength of composite-produced. Those raw materials preliminary were mixed by simple mixing with varied compositions and then hot-pressed at 36 MPa and 100 ░C for 20 minutes. From compressive strength test, it was found that composite with composition 7:8 of PVAc and leaves-waste had maximum compressive strength, i.e. 57.60 MPa. It was also that the enhancement of strength due to PVAc fraction (w/w) increasing is a percolation behavior, even though its mathematical explanation has not been performed. Into composition of maximum strength above, silica with average size is 74 nm then was added to improve the strength and found that at silica weight fraction of 0.79 (%w/w), the composite had optimum compressive strength, i.e. 70.5 MPa, or increased up to 22.4% of that without silica. The final compressive strength was very comparable to some building goods such as sandstones and bricks. The composite density was also measured and obtained that it was about 0.9 g/cm3 that is very close to some usual woods.
Masturi, Masturi; Aliah, Hasniah; Aji, Mahardika Prasetya; Sagita, Adi Ardian; Bukit, Minsyahril; Sustini, Euis; Khairurrijal, Khairurrijal; Abdullah, Mikrajuddin
Genera and species in acetic acid bacteria.
Taxonomic studies of acetic acid bacteria were historically surveyed. The genus Acetobacter was first introduced in 1898 with a single species, Acetobacter aceti. The genus Gluconobacter was proposed in 1935 for strains with intense oxidation of glucose to gluconic acid rather than oxidation of ethanol to acetic acid and no oxidation of acetate. The genus "Acetomonas" was described in 1954 for strains with polar flagellation and no oxidation of acetate. The proposals of the two generic names were due to confusion, and "Acetomonas" was a junior subjective synonym of Gluconobacter. The genus Acetobacter was in 1984 divided into two subgenera, Acetobacter and Gluconoacetobacter. The latter was elevated to the genus Gluconacetobacter in 1998. In the acetic acid bacteria, ten genera are presently recognized and accommodated to the family Acetobacteraceae, the Alphaproteobacteria: Acetobacteer, Gluconobacter, Acidomonas, Gluconacetobacter, Asaia, Kozakia, Swaminathania, Saccharibacter, Neoasaia and Granulibacter. In contrast, the genus Frateuria, strains of which were once named 'pseudacetic acid bacteria', was classified into the Gammaproteobacteria. The genus Gluconacetobacter was phylogenetically divided into two groups: the Gluconacetobacter liquefaciens group and the Gluconacetobacter xylinus group. The two groups were discussed taxonomically. PMID:18199517
Yamada, Yuzo; Yukphan, Pattaraporn
Acetate reduces microglia inflammatory signaling in vitro
Acetate supplementation increases brain acetyl-CoA and histone acetylation and reduces lipopolysaccharide (LPS)-induced neuroglial activation and interleukin (IL)-1? expression in vivo. To determine how acetate imparts these properties, we tested the hypothesis that acetate metabolism reduces inflammatory signaling in microglia. To test this, we measured the effect acetate treatment had on cytokine expression, mitogen-activated protein kinase (MAPK) signaling, histone H3 at lysine 9 acetylation, and alterations of nuclear factor-kappa B (NF-?B) in primary and BV-2 cultured microglia. We found that treatment induced H3K9 hyperacetylation and reversed LPS-induced H3K9 hypoacetylation similar to that found in vivo. LPS also increased IL-1?, IL-6 and tumor necrosis factor-alpha (TNF-?) mRNA and protein, while treatment returned the protein to control levels and only partially attenuated IL-6 mRNA. In contrast, treatment increased mRNA levels of transforming-growth factor-?1 (TGF-?1) and both IL-4 mRNA and protein. LPS increased p38 MAPK and JNK phosphorylation at 4 and 2¢4 hr respectively, while treatment reduced p38 MAPK and JNK phosphorylation only at 2 hr. In addition, treatment reversed the LPS-induced elevation of NF-?B p65 protein and phosphorylation at serine 468 and induced acetylation at lysine 310. These data suggest that acetate metabolism reduces inflammatory signaling and alters histone and non-histone protein acetylation.
Soliman, Mahmoud L.; Puig, Kendra L.; Combs, Colin K.; Rosenberger, Thad A.
Atmospheric oxidation pathways of acetic acid.
One of the most abundant carboxylic acids measured in the atmosphere is acetic acid (CH(3)C(O)OH), present in rural, urban, and remote marine environments in the low-ppb range. Acetic acid concentrations are not well reproduced in global 3-D atmospheric models because of the poor inventory of sources and sinks to model its global distribution. To understand the complete oxidation of acetic acid in the atmosphere initiated by OH radicals, ab initio calculations are performed to describe in detail the energetics of the reaction potential energy surface (PES). The proposed reaction mechanism suggests that the CH(3)C(O)OH + OH reaction takes place via three pathways: the addition of OH to the central carbon, the abstraction of a methyl hydrogen, and the abstraction of an acidic hydrogen. The PES is characterized by prereactive H-complexes, transition states, and more interestingly unique radical-mediated isomerization reactions. From the analysis of the energetics, acetic acid atmospheric oxidation will proceed mainly via the abstraction of the acidic hydrogen, consistent with previous experimental and theoretical studies. The major byproducts from each pathway are identified. Glyoxylic acid is suggested to be a major byproduct of the atmospheric oxidation of acetic acid. The atmospheric fate of glyoxylic acid is discussed. PMID:16571046
Rosado-Reyes, Claudette M; Francisco, Joseph S
A study of local crankshaft-type mobility in vitreous polyvinyl chloride and polyacrylonitrile by the method of conformational probes
Secondary relaxation transitions and local conformational dynamics in polyacrylonitrile and polyvinyl chloride were studied by the method of conformational probes. Relaxation transitions at 210 and 260 K (polyvinyl chloride) and 165 K (polyacrylonitrile) were explained by freezing of ōcrankshaft-typeö motions.
Kamalova, D. I.; Kolyadko, I. M.; Remizov, A. B.
FTIR studies of plasticized poly(vinyl alcohol)-chitosan blend doped with NH 4NO 3 polymer electrolyte membrane
Fourier transform infrared (FTIR) spectroscopy studies of poly(vinyl alcohol) (PVA), and chitosan polymer blend doped with ammonium nitrate (NH 4NO 3) salt and plasticized with ethylene carbonate (EC) have been performed with emphasis on the shift of the carboxamide, amine and hydroxyl bands. 1% acetic acid solution was used as the solvent. It is observed from the chitosan film spectrum that evidence of polymer-solvent interaction can be observed from the shifting of the carboxamide band at 1660 cm -1 and the amine band at 1591 cm -1 to 1650 and 1557 cm -1 respectively and the shift of the hydroxyl band from 3377 to 3354 cm -1. The hydroxyl band in the spectrum of PVA powder is observed at 3354 cm -1 and is observed at 3343 cm -1 in the spectrum of the PVA film. On addition of NH 4NO 3 up to 30 wt.%, the carboxamide, amine and hydroxyl bands shifted from 1650, 1557 and 3354 cm -1 to 1642, 1541 and 3348 cm -1 indicating that the chitosan has complexed with the salt. In the PVA-NH 4NO 3 spectrum, the hydroxyl band has shifted from 3343 to 3272 cm -1 on addition of salt from 10 to 30 wt.%. EC acts as a plasticizing agent since there is no shift in the bands as observed in the spectrum of PVA-chitosan-EC films. The mechanism of ion migration is proposed for the plasticized and unplasticized PVA-chitosan-NH 4NO 3 systems. In the spectrum of PVA-chitosan-NH 4NO 3-EC complex, the doublet C dbnd O stretching in EC is observed in the vicinity 1800 and 1700. This indicates that there is some interaction between the salt and EC.
Kadir, M. F. Z.; Aspanut, Z.; Majid, S. R.; Arof, A. K.
Multiple-hologram storage for thin layers of Methyl Orange dyes in polyvinyl alcohol matrices
We realized hologram storage within a 0.07-cm2 light spot in thin layers of polyvinyl alcohol matrices doped with Methyl Orange dyes preirradiated by the 488.0-nm line of an Ar-ion laser with two orthogonal linearly polarized 632.8-nm light beams. By rotation of the sample, multiple-hologram storage was achieved. By controlling the writing time, we have recorded three-hologram and five-hologram images in the same light spot. The mechanism of the multiple-hologram storage in Methyl Orange-doped polyvinyl alcohol thin films is discussed.
Liu, Yichun; Wang, Haiyu; Tian, Mingzhen; Lin, Jiulin; Kong, Xianggui; Huang, Shihua; Yu, Jiaqi
Structural and electronic properties of poly(vinyl alcohol) using density functional theory
The first principles calculations have been carried out to investigate the structural, electronic band structure density of states along with the projected density of states for poly(vinyl alcohol). Our structural calculation suggests that the poly(vinyl alcohol) exhibits monoclinic structure. The calculated structural lattice parameters are in excellent agreement with available experimental values. The band structure calculations reveal that the direct and indirect band gaps are 5.55 eV and 5.363 eV respectively in accordance with experimental values.
Dabhi, Shweta; Jha, Prafulla K.
Cytenamide trifluoro-acetic acid solvate
Cytenamide forms a 1:1 solvate with trifluoroŁacetic acid (systematic name: 5H-dibenzo[a,d]cycloŁheptaŁtriene-5-carboxamide trifluoroŁacetic acid solvate), C16H13NOĘC2HF3O2. The compound crystallizes with one molŁecule of cytenamide and one of trifluoroŁacetic acid in the asymmetric unit; these are linked by OŚH?O and NŚH?O hydrogen bonds to form an R 2 2(8) motif. The trifluoroŁmethyl group of the solvent molŁecule displays rotational disorder over two sites, with site-occupancy factors of 0.964?(4) and 0.036?(4).
Johnston, Andrea; Florence, Alastair J.; Fabbiani, Francesca J. A.; Shankland, Kenneth; Bedford, Colin T.; Bardin, Julie
Dynamic Protonation Equilibrium of Solvated Acetic Acid
For the first time, the dynamic protonation equilibrium between an amino acid side chain analogue and bulk water as well as the diffusion properties of the excess proton were successfully reproduced through unbiased computer simulations. During a 50 ns Q-HOP MD simulation, two different regimes of proton transfer were observed. Extended phases of frequent proton swapping between acetic acid and nearby water were separated by phases where the proton freely diffuses in the simulation box until it is captured again by acetic acid. The pKa of acetic acid was calculated around 3.0 based on the relative population of protonated and deprotonated states and the diffusion coefficient of excess proton was computed from the average mean squared displacement in the simulation. Both calculated values agree well with the experimental measurements.
Gu, Wei; Frigato, Tomaso; Straatsma, TP; Helms, Volkhard H.
The physicochemical property characterization of agar acetate.
A series of agar acetates with different degree of substitution (DS) were prepared, and their properties were determined and analyzed. The results showed that the gelling temperature, the gel melting temperature, the gel strength, the gel hardness, the gel fracturability, the gel springiness and the solution apparent viscosity of agar acetates all decreased except that their gel cohesiveness increased with the increase of DS. The variation process of agar molecules in solution from coil to helix could be also observed by measuring solution optical rotation in a lower concentration at which even the solution could not form a gel. The gel skeleton structures of agar acetates were of porous network structures, and the pores became smaller and denser with the increase of DS. After acetylation, the water holding capacity of the agar was improved, but its thermal stability was lowered. PMID:24906725
Xia, Kai; Liu, Xin; Zhao, Jingkun; Zhang, Xiaodong
Leuprolide acetate-induced generalized papular eruption.
Leuprolide acetate, a gonadotropin-releasing hormone agonist, is used in the treatment of prostate cancer. We report a unique case of a disseminated papular rash following leuprolide acetate injections in a 65-year-old man that shares clinical and histopathological features of papuloerythroderma of Ofuji. Leuprolide-induced papuloerythroderma, as well as a limited number of other disseminated cutaneous eruptions caused by this drug, is extremely rare, with only one case previously reported. Our case calls attention to this uncommon side effect in a commonly used hormonal therapy. J Drugs Dermatol. 2014;13(6):755-757. PMID:24918569
Burris, Katy; Ding, Catherine Y; Lim, Geoffrey F S
High performance ultrafiltration composite membranes based on poly(vinyl alcohol) hydrogel coating on crosslinked nanofibrous poly(vinyl alcohol) scaffold
A new kind of high flux ultrafiltration (UF) membrane based on poly(vinyl alcohol) (PVA) electrospun nanofibrous scaffold support and PVA hydrogel coating has been demonstrated. The long-term performance of such membranes was optimized by a variation of degree of hydrolysis (i.e. 88¢99%) and molecular weight (e.g. 13,000¢124,000g\\/mol) in the electrospun PVA scaffold in conjunction with chemical crosslinking of PVA hydrogel
Xuefen Wang; Dufei Fang; Kyunghwan Yoon; Benjamin S. Hsiao; Benjamin Chu
Phorbol Myristate Acetate-Induced Macrophage Aggregation
Phorbol myristate acetate (PMA) at nanomole concentrations induces a rapid aggregation of guinea pig macrophages. This aggregation is dependent on extracellular Mg2+ (but not Ca2+) for its development. Additionally, it is inhibited by some agents which also inhibit aggregation induced by lymphokines and the ionophore A23187. Although the mechanism of aggregation has not been determined, it does not appear to
P. Badenoch-Jones
21 CFR 582.6185 - Calcium acetate.
21 Ū Food and Drugs Ū 6 Ū 2013-04-01 Ū 2013-04-01 Ū false Ū Calcium acetate. Ū 582.6185 Ū Section 582.6185 Ū Food and Drugs Ū FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) Ū ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS Ū SUBSTANCES GENERALLY RECOGNIZED AS SAFE...
Treatment of Pedophilia with Leuprolide Acetate
To date, the literature on the treatment of individuals who have committed sexual offenses has focused primarily on psychotherapeutic interventions and the use of antiandrogens. Recently case reports and small series supporting the efficacy of other psychiatric medication, such as serotonin reuptake inhibitors, have been published. Only a few publications have looked at the efficacy of leuprolide acetate, an LH-RH
Nancy Raymond; Bean Robinson; Chris Kraft; Barry Rittberg; Eli Coleman
Corrosion of stainless steel during acetate production
Corrosion of types 304, 304L, 316, and 316L stainless steel (SS) during the esterification of acetic acid and alcohol or glycol ether was investigated. The catalyst for this reaction, sulfuric acid or para-toluene sulfonic acid (PTSA), was shown to cause more corrosion on reactor equipment than CH{sub 3}COOH under the process conditions commonly practiced in industry. The corrosive action of the catalyst occurred only in the presence of water. Thus, for the batch processes, corrosion occurred mostly during the initial stage of esterification, where water produced by the reaction created an aqueous environment. After water was distilled off, the corrosion rate declined to a negligible value. The corrosion inhibitor copper sulfate, often used in industrial acetate processes, was found to work well for a low-temperature process (< 95 C) such as in production of butyl acetate, but it accelerated corrosion in the glycol ether acetate processes where temperatures were > 108 C. Process conditions that imparted low corrosion rates were determined.
Qi, J.S.; Lester, G.C. [Occidental Chemical Corp. Technology Center, Grand Island, NY (United States)
Megestrol acetate in cachexia and anorexia.
The aim is to review major clinical trials that have used megestrol acetate (MA) in the treatment of cachexia across several disease states. A review of general usage and potential side-effects are discussed. A theory that the newly approved nanocrystal formation of MA can better deliver this potent medication for treatment will also be reviewed. PMID:17722275
Yeh, Shing-Shing; Schuster, Michael W
Process for the preparation of vinyl acetate
This invention pertains to the preparation of vinyl acetate by contacting within a contact zone a mixture of ketene and acetaldehyde with an acid catalyst at about one bar pressure and between about 85 and 200 C and removing the reaction products from the contact zone.
Immunotoxicity of Trenbolone Acetate in Japanese Quail
Trenbolone acetate is a synthetic androgen that is currently used as a growth promoter in many meat-exporting countries. Despite industry laboratories classifying trenbolone as nonteratogenic, data showed that embryonic exposure to this androgenic chemical altered development of the immune system in Japanese quail. Trenbolone is lipophilic, persistent, and released into the environment in manure used as soil fertilizer. This is
Michael James Quinn; Moira McKernan; Emma T. Lavoie; Mary Ann Ottinger
Pregnancy Following Uterine Artery Embolization with Polyvinyl Alcohol Particles for Patients with Uterine Fibroid or Adenomyosis
Purpose: To determine whether uterine fibroid embolization (UFE) with polyvinyl alcohol (PVA) particles affects fertility in women desiring future pregnancy. Methods: Of 288 patients managed with UFE with PVA particles for uterine myoma or adenomyosis between 1998 and 2001, 94 patients were enrolled in this study. The age range of participants was 20¢40 years. The data were collected through review
Man Deuk Kim; Nahk Keun Kim; Hee Jin Kim; Mee Hwa Lee
Nonlinear-optical properties of a poly(vinyl alcohol)-polyaniline interpenetrating polymer network
The nonlinear-optical properties of a semi-interpenetrating polymer network of poly(vinyl alcohol) glutaraldehyde-polyaniline were studied. Large ( 10-12 cm2 / W) and fast ( < 50 ps) refractive optical nonlinearites were observed. The potential of this novel material for photonic applications is evaluated.
Petrov, D. V.; Gomes, A. S. L.; de Ara·jo, Cid B.; de Souza, J. M.; de Azevedo, W. M.; de Melo, J. V.; Diniz, F. B.
In vivo calcium deposition on polyvinyl alcohol matrix used in hollow fiber cell macroencapsulation devices
The encapsulation of genetically modified cells represents a promising approach for the delivery of therapeutic proteins. The functionality of the device is dependent on the characteristics of the biomaterials, the procedures used in its confection and the adaptability of the encapsulated cells in the host. We report conditions leading to the development of calcifications on the polyvinyl alcohol (PVA) matrix
F. Schwenter; N. Bouche; W.-F. Pralong; P. Aebischer
Development of polyvinyl alcohol shells overcoated with polystyrene layer for inertial confinement fusion experiments
In inertial fusion experiments, the use of polymer shells provides more efficient ablative implosion and significantly reduced radiation preheat compared with the glass shells currently used. We have developed a method of fabricating polyvinyl alcohol (PVA) shells overcoated with a polystyrene (PS) layer. The method utilizes the emulsion technique previously developed by us, and employs three different liquid phases. A
Uichi Kubo; Hiroshi Tsubakihara
Neutron attenuation characteristics of polyethylene, polyvinyl chloride, and heavy aggregate concrete and mortars
Polyethylene and polyvinyl chloride pellets were introduced into concrete to improve its neutron attenuation characteristics while several types of heavy coarse aggregates were used to improve its gamma ray attenuation properties. Neutron and gamma ray attenuation were studied in concrete samples containing coarse aggregates of barite, pyrite, basalt, hematite, and marble as well as polyethylene and polyvinyl chloride pellets in narrow-beam geometry. The highest neutron attenuation was shown by polyethylene mortar, followed by polyvinyl chloride mortar; barite and pyrite concrete showed higher gamma ray attenuation than ordinary concrete. Broad-beam and continuous (infinite) medium geometries were used to study the neutron attenuation of samples containing polymers at different concentrations with and without heavy aggregates, the fitting equations were established, and from these the neutron removal coefficients were deduced. In a radiation field of neutrons and gamma rays, the appropriate concentration of polymer and heavy aggregate can be selected to give the optimum total dose attenuation depending on the relative intensities of each type of radiation. This would give much better design flexibility over ordinary concrete. The compressive strength tests performed on mortar and concrete samples showed that their value, in general, decreases as polymer concentration increases and that the polyvinyl chloride mortar showed higher values than the polyethylene mortar. For general construction purposes, the compression strength was considered acceptable in these samples. 34 refs., 16 figs., 4 tabs.
Abdul-Majid, S.; Othman, F. [King Abdulaziz Univ., Jeddah (Saudi Arabia)
Mechanism of growth of colloidal silver nanoparticles stabilized by polyvinyl pyrrolidone in ?-irradiated silver nitrate solution
Silver nanoparticles were prepared by using polyvinyl pyrrolidone (PVP) as a stabilizer and ?-irradiation. Transmission electron microscopy (TEM) results showed that both the amount and the molecular weight of PVP in the irradiated solution considerably affect the average size of the silver nanoparticles. The average size of the silver nanoparticles decreases with increasing the amount of PVP in the solution,
Hyeon Suk Shin; Hyun Jung Yang; Seung Bin Kim; Mu Sang Lee
Studies in Plasticization of Polyvinyl Chloride. II. Plasticizer Variations in PVC-Plasticizer Systems
Polyvinyl chloride resin is softened by certain liquids, called plasticizers, through a set of processes with high activation energies, 50¢100 kcal. At fixed temperature, ``reaction'' rates are directly proportional to vapor pressure of the liquid. The dielectric change may be treated similarly to a chemical reaction between a solid and a vapor, and free energy of activation, ?F**, evaluated. ?F**
M. L. Dannis
Amino acid metabolism of preimplantation bovine embryos cultured with bovine serum albumin or polyvinyl alcohol
Bovine serum albumin (BSA) is an embryotrophic macromolecule used in embryo culture media, which is commonly replaced with synthetic compounds, such as polyvinyl alcohol (PVA). This study compared the effect of BSA and PVA on the development, blastocyst cell number and amino acid metabolism of preimplantation bovine embryos in vitro. Embryos were produced by in vitro maturation and fertilization of
Nicolas M Orsi; Henry J Leese
Poly(vinyl alcohol)¢collagen hydrolysate thermoplastic blends: I. Experimental design optimisation and biodegradation behaviour
Hybrid blends based on poly(vinyl alcohol) (PVA) and collagen hydrolysate (CH), an abundant, added value waste product of the leather industry, have been processed by melt blow extrusion to environmentally degradable films. Optimisation of the blend compositions was performed in respect of mechanical properties of the films. The experimental design method (DOE) was used for the understanding of the structure¢property
P. Alexy; D. BakoÜ; S. Hanzelovß; L. KukolĒkovß; J. Kupec; K. Charvßtovß; E. Chiellini; P. Cinelli
Allergic contact dermatitis from a pyridine derivative in polyvinyl chloride leather
Antimicrobial coating of household products has gained wide acceptance in Japan in the past several years. Pyridine derivatives, used as antifungal or antibacterial agents in many common products, are known to cause contact dermatitis. We present a case of severe contact dermatitis caused by a pyridine derivative used as an antifungal agent in the polyvinyl chloride (PVC) leather of a
Wook-Kang Huh; Yutaka Masuji; Joji Tada; Jir¶ Arata; Masaaki Kaniwa
Formation of carbon nanotubes from polyvinyl alcohol using arc-discharge method
The aim of this study is to investigate the possibility of using a polymer material, polyvinyl alcohol (PVA), as an additional carbon source to fabricate carbon nanotubes using arc-discharge method. Experiments were carried out using a graphite anode filled with a mixture of PVA and iron group catalysts. The results indicated that PVA material not only can be used for
Yu-Hsiang Wang; Sheng-Cheng Chiu; Kuo-Min Lin; Yuan-Yao Li
Rheological behaviour of irradiated wound dressing poly(vinyl pyrrolidone) hydrogels
The use of hydrogels as biomaterials has increased lately. Poly(vinyl pyrrolidone) (PVP) is an example of polymer hydrogels applied for the synthesis of hydrogel to be used in different biomedical applications. This paper describes a study on rheological properties of PVP hydrogels obtained by gamma radiation techniques. PVP hydrogels were obtained by gamma radiation of PVP water solutions with different
Ademar B LugŃo; Sizue O Rogero; S¶nia M Malmonge
Glass transition behavior of the vitrification solutions containing propanediol, dimethyl sulfoxide and polyvinyl alcohol
Knowledge of the glass transition behavior of vitrification solutions is important for research and planning of the cryopreservation of biological materials by vitrification. This brief communication shows the analysis for the glass transition and glass stability of the multi-component vitrification solutions containing propanediol (PE), dimethyl sulfoxide (Me2SO) and polyvinyl alcohol (PVA) by using differential scanning calorimetry (DSC) during the cooling
Hai-Yan Wang; Shu-Shen Lu; Zhao-Rong Lun
Thermal analysis of poly(vinyl alcohol)\\/graphite oxide intercalated composites
Poly(vinyl alcohol)\\/graphite oxide intercalated nanocomposites have been prepared and characterized by X-ray diffraction. Their differential scanning calorimetry and thermogravimetry results suggest that the content of graphite oxide change the glass transition temperature of nanocomposites, and the increase of graphite oxide content can cause the increase of the oxidation temperature of nanocomposites and decrease of their mass loss rate.
Jiayan Xu; Yuan Hu; Lei Song; Qingan Wang; Weicheng Fan; Guangxuan Liao; Zuyao Chen
Pegylated enzyme entrapped in poly(vinyl alcohol) hydrogel for biocatalytic application
A procedure for enzyme entrapment into matrices suitable for biocatalytic applications is reported. The method, which takes advantage of the stable formation of polyvinyl alcohol (PVA) hydrogels by freezing and thawing PVA aqueous solutions, was assayed using lipase as model enzyme. The leakage of lipase was minimised by using high molecular weight PVA and by previous conjugation of the enzyme
Francesco Maria Veronese; Cristina Mammucari; Franco Schiavon; Odolone Schiavon; Silvano Lora; Francesco Secundo; Adriana Chilin; Adriano Guiotto
Properties of composites based on polyvinyl alcohol containing biologically active substances and films made of them
The effect of the composition of spinning composites based on polyvinyl alcohol containing biologically active substances on their rheological properties and the structure of films fabricated from these composites by the dry method was investigated. It was shown that addition of protein and antimicrobial substances to the composite and alteration of the spinning temperature result in films of different structure
N. R. Kil'deeva; S. P. Trusova; N. S. Pilevskaya; A. D. Virnik
Development of Meloxicam-Loaded Electrospun Polyvinyl Alcohol Mats as a Transdermal Therapeutic Agent
This study reports on the use of electrospun polyvinyl alcohol (PVA) nanofiber mats loaded with meloxicam (MX) as a transdermal drug delivery system. The amounts of MX loaded in the base PVA solution (10% w\\/v solution) were 2.5, 5, 10 and 20% weight, based on the dry weight of PVA (% wt). The average diameters of these fibers ranged from
Tanasait Ngawhirunpat; Praneet Opanasopit; Theerasak Rojanarata; Prasert Akkaramongkolporn; Uracha Ruktanonchai; Pitt Supaphol
Use of polyvinyl alcohol as a stabilizer of peroxidase-antibody conjugate for enzyme immunoassay
The activity of a peroxidase-antibody conjugate was greatly stabilized while in solution through the addition of polyvinyl alcohol (PVA). This stabilizing effect was dependent upon the molecular weight and degree of hydrolysis of the PVA used. The concentrations of PVA necessary for maximum stabilization had no adverse effects upon enzyme immunoassay. Thus, the conjugate stabilized by PVA can be used
Scott Boyd; Hiroshi Yamazaki
Structure of polyvinyl alcohol membranes containing pepsin immobilized at temperatures below 0░C
For the effective functioning of enzymes, it is recommended that they be used in an immobilized form. Polyvinyl alcohol (PVA) is one of the most widespread polymer supports for enzymes. PVA is promising for the development of matrices with immobilized enzymes due to its hydrophiticity and a number of structure-related transport properties. In this work we studied pepsin, which is
R. Yu. Kosenko; A. L. Iordanskii; L. I. Bulatnikova; O. N. Belyatskaya; L. V. Bykova
Electrospun poly(vinyl alcohol)\\/glucose oxidase biocomposite membranes for biosensor applications
A novel technique for enzyme immobilization on the surface of the Au electrode for designing amperometric biosensor by electrospinning poly(vinyl alcohol) (PVA) and glucose oxidase (GOD) is presented in this paper. The immobilized GOD remained active inside the electrospun PVA fibrous membranes. The membranes are promising candidates for immobilization of enzymes because of their high specific surface area and porous
Guanglei Ren; Xinhua Xu; Qiang Liu; Juan Cheng; Xiaoyan Yuan; Lili Wu; Yizao Wan
Magnetic polymers of maghemite (?-Fe 2O 3) and polyvinyl alcohol
Oxide particles synthesized and dispersed in aqueous medium, containing different polymeric forms, can be trapped in solid matrices keeping a high dispersion degree. The oxide\\/polymer mass ratio determines the average distance between the particles existing in the sol. In this work, ultrafine maghemite particles were prepared in aqueous solution containing different concentrations of polyvinyl alcohol (PVA). The average diameter of
Cecilia Albornoz; Elsa E. Sileo; Silvia E. Jacobo
Investigation of Miscibility of Linseed Oil Epoxy with Poly(vinyl alcohol)
Blending of two polymers in solution is a simple and cost effective technique to improve upon the physical and mechanical properties of the component polymers. Maximum synergism in the properties of the two polymers occurs when they are thermodynamically miscible. Poly(vinyl alcohol) (PVA) yields tough, flexible and water sensitive films. Linseed oil epoxy(LOE), a product from sustainable resource, used as
S. M. Ashraf; Sharif Ahmad; Ufana Riaz; Manawwer Alam; H. O. Sharma
Compatibility of Polyvinyl Alcohol with the 241-F/H Tank Farm Liquid Waste.
This report describes results from laboratory-scale oxidative mineralization of polyvinyl alcohol (PVA), and the evaluation of the F/H Tank Farms as a storage/disposal option for PVA waste solution generated in the Canyons and B-line decontamination opera...
L. N. Oji
Ionic reactions in pulse irradiated poly(vinyl chloride) filmŚthe effect of plasticizers
Poly(vinyl chloride), PVC+plasticizer (DEHP, TOTM) films were pulse irradiated using electron accelerator and the transient species generated in these matrices were analysed. The absorption spectra of plasticizers ions (anion and cation type) were identified in PVC system using as a model 2-propanol and sec-butyl chloride solutions of respective plasticizers. The mechanism of reactions is proposed and discussed.
J. Mayer; M. Szadkowska-Nicze
Testing of polyvinyl alcohol and starch mixtures as biodegradable polymeric materials
The mechanical properties, thermal behaviour and biodegradation of some polymeric materials based on polyvinyl alcohol and starch, in the presence of urea (used as a micro-organism nitrogen source\\/plasticizer) and glycerine (used as a plasticizer) have been studied. The chemical composition optimization of the analysed blends was carried out using a second order factorial experimental design. The progress of biodegradation was
N Tudorachi; C. N Cascaval; M Rusu; M Pruteanu
Efficacy of Trisacryl Gelatin Microspheres versus Polyvinyl Alcohol Particles in the Preoperative Embolization of Meningiomas
BACKGROUND AND PURPOSE: Trisacryl gelatin microspheres are a new, commercially available nonabsorbable embolic agent. The purpose of this study was to evaluate their efficacy in the preoperative embolization of meningiomas as compared with polyvinyl alcohol (PVA) particles of various sizes. METHODS: In 30 consecutive patients, trisacryl gelatin microspheres (150-300 mm) were used for the preoperative superselective embolization of meningiomas (group
Martin Bendszus; Rudiger Klein; Ralf Burger; Monika Warmuth-Metz; Erich Hofmann; Laszlo Solymosi
Effect of surface modifications of leather on its joint strength with polyvinyl chloride
The treatment of bovine leathers with wetting and lyotropic agents followed by heating produced a strengthening of the leathers which increased their joint strength properties to polyvinyl chloride (PVC). A cohesive failure of leather was always obtained. The highest cohesive strength (or point peel strength) was obtained when the treatment was carried out at 140░C with the surfactant NFOE (8.5)
T. P. Ferrßndiz-G¾mez; M. Almela; J. M. MartĒn-MartĒnez; F. Maldonado; A. C. Orgilķs-Barcel¾
Modeling water states in polyvinyl alcohol-fumed silica nano-composites
We proposed a mathematical model to account for water contents in different states as a function of filler concentration in polymer¢filler composites. The water states were characterized in polyvinyl alcohol (PVA) and PVA¢fumed silica (FS) composites using low temperature differential scanning calorimetry. This model takes into consideration the inert filler dilution effect, the equilibrium of bound water to free and
Shingjiang Jessie Lue; Song-Jiang Shieh
A Reactive Blending Method for Preparation of Polyvinyl Chloride\\/Thermosetting Polyurethane Blends
An attempt was made to prepare polyvinyl chloride (PVC)\\/thermosetting polyurethane (PU) blends via direct formation of the thermosetting minor phase from its reactants during blending into PVC. Chemorheological approaches were employed in order to investigate the formation reaction of PU. The results of chemorheological analyses were utilized to adjust appropriate reactive blending temperature. PVC\\/PU reactive blending process was carried out
Hamed Haddadi; Navid M. Famili
Irradiation crosslinking of unplasticized polyvinyl chloride in the presence of additives
Electron beam initiated crosslinking of unplasticized polyvinyl chloride, UPVC, has been carried out over a range of irradiation doses (20¢200 kGy). The effects of trimethylolpropane triacrylate (TMPTA) and Irganox 1010 on the rate of crosslinking were also studied. Changes in gel fraction, hardness, tensile strength and damping properties upon irradiation were investigated. Results revealed that under the irradiation conditions employed,
Chantara Thevy Ratnam; M Nasir; A Baharin
Polyvinyl chloride toxicity in fires. Hydrogen chloride toxicity in fire fighters.
Polyvinyl chloride, of all the plastic polymers, has been implicated primarily in causing the most serious problem in fire fighting today because it releases hydrogen chloride gas when burning. One hundred seventy fire fighters who experienced symptoms from its toxicity have been studied from 1970 to 1975. One died. PMID:946083
Dyer, R F; Esch, V H
Method of Cross-Linking Polyvinyl Alcohol and Other Water Soluble Resins.
A self-supporting sheet structure comprising a water soluble, non-cross-linked polymer, such as polyvinyl alcohol, is reported which is capable of being cross-linked by reaction with hydrogen atom radicals and hydroxyl molecule radicals in an aqueous solu...
D. W. Sheibley W. H. Philipp L. C. Hsu
Characterization of Poly(Vinyl Chloride) Aged in a Bromine Containing Electrolyte.
Poly(vinyl chloride) (PVC) is being considered for use as a flow frame material in a developmental zinc/bromine battery. The choice of PVC was based on its low cost and the ease with which it can be molded into complex parts. The electrolyte used in this ...
C. Arnold A. Leo M. Tarjani
Intracellular proliferation of Legionella pneumophila in Hartmannella vermiformis in aquatic biofilms grown on plasticized polyvinyl chloride
The need for protozoa for the proliferation of Legionella pneumophila in aquatic habitats is still not fully understood and is even questioned by some investigators. This study shows the in vivo growth of L. pneumophila in protozoa in aquatic biofilms developing at high concentrations on plasticized polyvinyl chloride in a batch system with autoclaved tap water. The inoculum, a mixed
Melanie W. Kuiper; Bart A. Wullings; Antoon D. L. Akkermans; Rijkelt R. Beumer; Dick van der Kooij
Degradation and stabilization of poly (vinyl chloride). V. Reaction mechanism of poly(vinyl chloride) degradation
The degradation of poly(vinyl chloride) is a complex chain dehydrochlorination that consists of an initiation process to generate an active intermediate and a series of chain reactions that generates additional active intermediates with progressively increased numbers of double bonds. Each intermediate partitions between an intermediate with one more double bond and a stable conjugated polyene with the same number of
Radu Bacaloglu; Michael Fisch
Orientational photorefractive effects observed in poly(vinyl alcohol)/liquid crystal composites
We successfully observed orientational photorefractive gratings generated in poly(vinyl alcohol) (PVA)/liquid crystal (LC) composites doped with a fullerene (C60) as a photoconductive sensitizer under an applied dc field. Orientational photorefractivity was demonstrated by observing Raman-Nath diffraction beams with an external dc field. The photorefractive gratings were partially memorized even in the absence of the applied dc field.
Ono, Hiroshi; Saito, Isao; Kawatsuki, Nobuhiro
Cellulose nanofiber reinforced poly(vinyl alcohol) composite film with high visible light transmittance
In this paper, we presented the fabrication and characterization of poly(vinyl alcohol) (PVA) composite film reinforced with high volume of electrospun cellulose nanofibrous mat (CNM). Its visible light transmittance and mechanical properties were examined in relation to fiber content in the composite. Optimal CNM content in the composite was found to be 40wt% in terms of its overall properties. This
Chunyi Tang; Haiqing Liu
21 CFR 522.2477 - Trenbolone acetate and estradiol.
...confinement for slaughter Ō(i) Amount. (A) 120 milligrams (mg) trenbolone acetate and 24 mg estradiol (one implant consisting of 6 pellets, each pellet containing 20 mg trenbolone acetate and 4 mg estradiol) per implant dose....
Formulation and characterization of modified release tablets containing isoniazid using swellable polymers.
The aim of this work was to develop swellable modified release (MR) isoniazid tablets using different combinations of polyvinyl acetate (PVAc) and sodium-carboxymethylcellulose (Na-CMC). Granules were prepared by moist granulation technique and then compressed into tablets. In vitro release studies for 12 hr were carried out in dissolution media of varying pH i.e. pH 1.2, 4.5, 7.0 and 7.5. Tablets of all formulations were found to be of good physical quality with respect to appearance (width and thickness), content uniformity, hardness, weight variation and friability. In vitro release data showed that increasing total polymer content resulted in more retarding effect. Formulation with 35% polymer content exhibited zero order release profile and it released 35% of the drug in first hr, later on, controlled drug release was observed upto the 12(th) hour. Formulations with PVAc to Na-CMC ratio 20:80 exhibited zero order release pattern at levels of studied concentrations, which suggested that this combination can be used to formulate zero order release tablets of water soluble drugs like isoniazid. Korsmeyer-Peppas modeling of drug release showed that non-Fickian transport is the primary mechanism of isoniazid release from PVAc and Na-CMC based tablets. The value of mean dissolution time decreased with the increase in the release rate of drug clearly showing the retarding behavior of the swellable polymers. The application of a mixture of PVAc to Na-CMC in a specific ratio may be feasible to formulate zero order release tablets of water soluble drugs like isoniazid. PMID:22468003
Akhtar, M F; Rabbani, M; Sharif, A; Akhtar, B; Saleem, A; Murtaza, G
Separating acetic acid from furol (furfural) by electrodialysis method
Furfural production by hydrolysis of fibrous plant materials is accompanied by formation of acetic acid in amounts depending on the material used. The amount of acetic formed in the hydrolysis of the fruit shell of oil-tea camellia (Camellia oleosa) (an oilseed-bearing tree) is equal to the amount of furfural. The acetic acid can be separated from the furfural and concentrated to 10% by electrodialysis. A smaller amount of furfural is separated with acetic acid.
Guan, S.F.; Li, C.S. Ye, S.T.; Shen, S.Y.; Wang, Y.T.; Yu, S.H.
Gold-catalyzed cyclization of allenyl acetal derivatives
Summary The gold-catalyzed transformation of allenyl acetals into 5-alkylidenecyclopent-2-en-1-ones is described. The outcome of our deuterium labeling experiments supports a 1,4-hydride shift of the resulting allyl cationic intermediates because a complete deuterium transfer is observed. We tested the reaction on various acetal substrates bearing a propargyl acetate, giving 4-methoxy-5-alkylidenecyclopent-2-en-1-ones 4 via a degradation of the acetate group at the allyl cation intermediate.
Vasu, Dhananjayan; Pawar, Samir Kundlik
l-Lysinium trifluoro-acetate
Ions of the title compound, C6H15N2O2 +ĘC2F3O2 ?, a new organic nonlinear optical crystal, are linked by NŚH?O hydrogen-bonding interŁactions. Both the amino groups of the l-lysinium cation are protonated. A three-dimensional network of hydrogen bonds is observed, forming a closed ring. InterŁmolecular NŚH?O hydrogen bonds involving l-lysinium cations and trifluoroŁacetate anions link the ions into extended chains which run parallel to the [010] direction. The F atoms of the trifluoroŁacetate anion are disordered over two sites with site occupancies of 0.423?(18) and 0.577?(18). The asymmetric unit consists of two cations and two anions.
Sun, Zhi Hua; Fan, Jian Dong; Zhang, Guang Hui; Wang, Xin Qiang; Xu, Dong
Acetate kinase: not just a bacterial enzyme.
The bacterial enzymes acetate kinase (AK) and phosphotransacetylase (PTA) form a key pathway for synthesis of the central metabolic intermediate acetyl coenzyme A (acetyl-CoA) from acetate or for generation of ATP from excess acetyl-CoA. Putative AK genes have now been identified in some eukaryotic microbes. In Chlamydomonas reinhardtii and Phytophthora species, AK forms a pathway with PTA. AK has also been identified in non-yeast fungi but these fungi do not have PTA. Instead, AK forms a pathway with D-xylulose 5-phosphate phosphoketolase (XFP), a pathway that was also previously found only in bacteria. In Entamoeba histolytica, neither PTA nor XFP was found as a partner for AK. Thus, eukaryotic microbes seem to have incorporated the 'bacterial' enzyme AK into at least three different metabolic pathways. PMID:16678422
Ingram-Smith, Cheryl; Martin, Stephen R; Smith, Kerry S
Acetic acid vapor levels associated with facial prosthetics
The use of Silastic Medical Adhesive Type A in the fabrication of facial prostheses may cause health hazards to the patient and the operator because of acetic acid emissions. Caution must be exercised to remove acetic acid vapors from the air and unliberated acetic acid from material applied directly to the skin.
McElroy, T.H.; Guerra, O.N.; Lee, S.A.
Quantitative synthesis of star-shaped poly(vinyl ether)s with a narrow molecular weight distribution by living cationic polymerization.
Star-shaped poly(vinyl ether)s with narrow molecular weight distributions were obtained from polymer-linking reactions of living polymers with a divinyl compound based on living cationic polymerization. For example, living polymers (DP(n) = 50-300) of isobutyl vinyl ether (IBVE), prepared with a cationogen/EtAlCl(2) at 0 degrees C in hexane in the presence of ethyl acetate, were allowed to react with a small amount of 1,4-cyclohexanedimethanol divinyl ether (DVE-1) to give a star-shaped poly(IBVE) in quantitative yield (100%). In addition, a notable feature of this star-shaped polymer was extremely narrow molecular weight distribution (M(w)/M(n) = 1.1-1.2). The structure of divinyl compounds and reaction conditions for the linking reaction are key factors for achieving quantitative yield of star-shaped polymers. To our best knowledge, this is the first example of selective preparation of star-shaped polymers with narrow molecular weight distribution via one-pot polymer-linking reactions, which has never been achieved in any other mechanisms. The M(w) and the number of arms per molecule ranged from 6 x 10(4) to 30 x 10(4) and 9 to 44, respectively. Thermosensitive star polymers were also synthesized in quantitative yield, and the products were found to undergo sensitive phase separation and physical gelation. PMID:16756304
Shibata, Takaho; Kanaoka, Shokyoku; Aoshima, Sadahito
In vitro and in vivo evaluation of novel osmotic pump tablets of isosorbide-5-mononitrate containing polyvinyl pyrrolidone (PVP) for controlled release.
A novel osmotic pump tablet with ethyl cellulose (EC) and polyvinyl pyrrolidone (PVP) as the semipermeable membrane and isosorbide-5-mononitrate (5-ISMN) as the model drug was formulated in this study. Zero order release kinetics were attained by avoiding aging during storage. Drug release increased with an increase in the percentage of PVP K30 in the semipermeable membrane. However, drug release decreased with increased coating weight. Drug release rates decreased continuously for tablets coated with EC/PEG4000 and cellulose acetate (CA)/PEG4000. This tendency was more marked with longer storage time. However, there was little change in drug release rates for tablets with a semipermeable membrane of EC/PVP K30 at 6, 12 or 24 months. The weight loss test also validated the results mentioned above. The relative bioavailability of the osmotic-pump tablets against the reference formulation in single and multiple dose regimens was 116.7 and 106.5, respectively. This means that the bioavailability of osmotic pump tablets using PVP as the plasticiser was equal to that of the reference formulation. In general, 5-ISMN osmotic pump tablets with a semipermeable membrane composed of EC/PVP K30 may be useful in providing constant drug delivery with minimum fluctuations during longer storage time. PMID:22957434
Li, Xin; Jiang, Qingwei; Du, Lina; Wang, Chenyun; Chi, Qiang
Determination of butyltin and octyltin stabilizers in poly(vinyl chloride) products by headspace solid-phase microextraction and gas chromatography with flame-photometric detection.
Headspace solid-phase microextraction (HS-SPME) and gas chromatography with flame photometric detection (GC-FPD) have been investigated for determination of butyltin and octyltin stabilizers in poly(vinyl chloride) (PVC) products. The organotin stabilizers were first released from the plastic matrix by dissolving the PVC sample in tetrahydrofuran (THF). The stabilizers were then hydrolyzed to the chloride forms, by treatment with 6 mol L(-1) HCl, then derivatized with sodium tetraethylborate (NaBEt4) in 0.2 mol L(-1) sodium acetate buffer (pH 4.5) at 50 degrees C. HS-SPME was performed with a fused-silica fiber coated with a 100-microm film of polydimethylsiloxane (PDMS). The collected organotin compounds were then desorbed in the GC injector at 280 degrees C and analyzed by GC-FPD. Linearity (r > or =0.994) over a concentration of approximately two orders of magnitude was usually obtained. Limits of quantitation (LOQ) of the four organotin compounds studied, viz., monobutyltin (MBT), dibutyltin (DBT), monooctyltin (MOT), and dioctyltin (DOT), were in the range 0.3-1.0 ng Sn mL(-1). Recovery was >90% for butyltins and >80% for octyltins. The method was validated by analyzing two reference standard PVC sheets with known organotin content. The applicability of the method to analysis of organotin stabilizers in commercial PVC products was also demonstrated. PMID:16896617
Ou, Qin-Ren; Whang, Chen-Wen
Phorbol myristate acetate-induced neutrophil autotoxicity
We have previously shown that in the presence of phorbol myristate acetate (PMA), neutrophils kill neoplastic cells as well as themselves. This PMA-induced neutrophil autotoxicity was markedly inhibited by catalase, suggesting that H2O2 directly or indirectly played an important role. In this study we compared PMA and H2O2 toxicity against human neutrophils. The effect of H2O2 was faster and more
Min-Fu Tsan; Rebecca C. Denison
Calcium magnesium acetate production and cost reduction
The New York State Energy Research and Development Authority (Energy Authority), Consolidated Edison Company of New York, Inc. (ConEd), the New York State Department of Transportation (NYSDOT), the New York State Thruway Authority (NYSTA), Chevron Chemical Company, the National Corn Growers Association (NCGA), and the Massachusetts Department of Public Works (MDPW) sponsored a research program to develop technology capable of producing Calcium Magnesium Acetate (CMA), an alternative road deicer, at a quality and cost which will allow its increased use. The objectives of this program were to determine the feasibility of: (1) producing CMA from regionally available waste and low grade organic feedstocks via biochemical engineering technologies; (2) operating the fermentation at concentrated product levels to reduce energy requirements and minimize drying process costs; (3) using this production approach to produce an environmentally acceptable CMA product; and (4) using and adapting an existing facility for a CMA commercial demonstration plant. The experimental program included:(1) selection of microorganisms for their ability to grow in the absence of sodium chloride and to tolerate high concentrations of calcium, magnesium, and acetate ions; (2) analysis of waste feedstocks for their potential conversion to acetate; (3) analysis of waste organic material for impurities in CMA that could carry over into the environment; (4) batch experiments to determine pH tolerance, growth in the absence of sodium chloride (NaCl), tolerance to magnesium, calcium and acetate ions, effect of substrate concentration, acid distribution, and acid production; and (5) semi-continuous laboratory scale anaerobic digestion experiments to determine loading rates, conversion efficiencies, and other design data. 67 refs., 33 figs., 66 tabs.
Leuschner, A.P.
Vinyl acetate polymerization by ionizing radiation
For this work an irradiation system to be used in the polymerization of the vinyl acetate in methylethylketone and in ethyl alcohol solution using the gamma radiation as initiator was projected and built. The molecular weights of the polymers obtained by irradiation with gamma rays in methylethylketone and in ethyl alcohol solution were 33,000 and 44,000g\\/mol, respectively. >From the characterization
A. C. Mesquita; M. N. Mori; J. M. Vieira; L. G. Andrade e. Silva
For this work an irradiation system to be used in the polymerization of the vinyl acetate in methylethylketone and in ethyl alcohol solution using the gamma radiation as initiator was projected and built. The molecular weights of the polymers obtained by irradiation with gamma rays in methylethylketone and in ethyl alcohol solution were 33,000 and 44,000g\\/mol, respectively. From the characterization
A. C Mesquita; M. N Mori; J. M Vieira; L. G. Andrade e Silva
Corrosion of Stainless Steel During Acetate Production
Corrosion of types 304, 304L, 316, and 316L stainless steel (SS) during the esterification of acetic acid and alcohol or glycol ether was investigated. The catalyst for this reaction, sulfuric acid or para-toluene sulfonic acid (PTSA), was shown to cause more corrosion on reactor equipment than CHŌCOOH under the process conditions commonly practiced in industry. The corrosive action of the
J. S. Qi; G. C. Lester
Ultrasound-assisted dyeing of cellulose acetate.
The possibility of reducing the use of auxiliaries in conventional cellulose acetate dyeing with Disperse Red 50 using ultrasound technique was studied as an alternative to the standard procedure. Dyeing of cellulose acetate yarn was carried out by using either mechanical agitation alone, with and without auxiliaries, or coupling mechanical and ultrasound agitation in the bath where the temperature range was maintained between 60 and 80 ░C. The best results of dyeing kinetics were obtained with ultrasound coupled with mechanical agitation without auxiliaries (90% of bath exhaustion value at 80 ░C). Hence the corresponding half dyeing times, absorption rate constants according to Cegarra-Puente modified equation and ultrasound efficiency were calculated confirming the synergic effect of sonication on the dyeing kinetics. Moreover the apparent activation energies were also evaluated and the positive effect of ultrasound added to mechanical agitation was evidenced by the lower value (48 kJ/mol) in comparison with 112 and 169 kJ/mol for mechanical stirring alone with auxiliaries and without, respectively. Finally, the fastness tests gave good values for samples dyed with ultrasound technique even without auxiliaries. Moreover color measurements on dyed yarns showed that the color yield obtained by ultrasound-assisted dyeing at 80 ░C of cellulose acetate without using additional chemicals into the dye bath reached the same value yielded by mechanical agitation, but with remarkably shorter time. PMID:24457001
Udrescu, C; Ferrero, F; Periolatto, M
Application of mixtures of polymeric carriers for dissolution enhancement of fenofibrate using hot-melt extrusion.
Hot-melt extrusion was applied to improve dissolution behavior of poorly soluble model drug fenofibrate. Blends of polymers were used as carrier: copovidone (COP), polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol copolymer (PVCL-PVAc-PEG) and hypromellose 2910/5 (HPMC). The ratio of fenofibrate to COP remained constantly 1+3 (weighted parts) with varying amounts of PVCL-PVAc-PEG and HPMC. Solid state of fenofibrate was characterized by X-ray diffractometry and differential scanning calorimetry. Dissolution performance was compared to marketed formulations Lipidil and Lipidil-Ter. Stability studies were conducted at 25░C/60%rH. The dissolution rate from extrudates was significantly increased when compared to pure fenofibrate powder or physical mixture of the components. A supersaturation of 7.6-12.1 was reached with the pelletized extrudates. All extrudates were superior to marketed formulations. No recrystallization was observed after 26 weeks of storage for fenofibrate-COP extrudates 1+3 (weighted parts) with or without polymeric additives. Even so, both degree and duration of supersaturation decreased with increasing storage periods with the exception of fenofibrate-HPMC extrudates. Of particular interest is the finding that by adding polymers with differing release characteristics to the drug-carrier mixture, the dissolution performance of hot-melt extruded solid dosage forms can be readily adapted to meet specific requirements. PMID:22440149
Kalivoda, Adela; Fischbach, Matthias; Kleinebudde, Peter
Comparison of Fire Sprinkler Piping Materials: Steel, Copper, Chlorinated Polyvinyl Chloride and Polybutylene, in Residential and Light Hazard Installations.
A literature based study was conducted at the Building and Fire Research Laboratory of the National Institute of Standards and Technology to compare characteristics and usage of steel, copper, chlorinated polyvinyl chloride and polybutylene fire sprinkler...
K. A. Notarianni M. A. Jackson
Polyvinyl chloride. January 1980-February 1992 (Citations from the NTIS Data Base). Rept. for Jan 80-Feb 92
The bibliography contains citations concerning preparation, properties, composition, toxicity, and health hazards of polyvinyl chloride. Topics include, aging tests, combustion products, occupational safety and health, photolysis, thermal degradation, and pollution. (Contains 116 citations with title list and subject index.)
Not Available
Pervaporation characteristics of ethylene¢vinyl acetate copolymer membranes with different composition for recovery of ethyl acetate from aqueous solution
The degree of crystallization, surface property and density of ethylene¢vinyl acetate (EVA) copolymer membranes with different vinyl acetate (VA) content were measured by differential scanning calorimetry (DSC), contact angle meter and pycnometer. The pervaporation (PV) characteristics of the EVA copolymer membranes for recovery of ethyl acetate (EA) from aqueous EA solutions have been investigated. The separation factor (?) decreased with
Yunxiang Bai; Jinwen Qian; Quanfu An; Zhihui Zhu; Peng Zhang
Tumor-promoting Activity of 2,3-Dihydrophorbol Myristate Acetate and Phorbolol Myristate Acetate in Mouse Skin1
Phorbolol myristate acetate (PHMA) had been previ ously prepared from the potent mouse skin tumor pro moter phorbol myristate acetate (PMA) by sodium boro- hydride reduction of the C-5 carbonyl group in PMA to a secondary alcohol. PHMA was shown to have an inflam matory effect in mouse skin equal to that of PMA. 2,3- Dihydrophorbol myristate acetate (DPMA), a
A. Segal; B. L. Van Duuren; J. J. Solomon; I. Seidman; A. Smith; S. Melchionne
Properties of poly(vinyl alcohol) fiber reinforced high-performance organic aggregate cementitious material: Converting brittle to plastic
This study focuses on the development of a lightweight high-performance cementitious composite material which is reinforced with poly(vinyl alcohol) (PVA) fiber and contains poly(vinyl butyral) (PVB) as the sole aggregate. Mechanical properties such as compressive and flexural strengths, impact resistance, and fracture toughness are evaluated. PVB composite produces low average density concrete of 1548kg\\/m3 (96.6 pcf) and a compressive strength
H. Toutanji; B. Xu; J. Gilbert; T. Lavin
Characterization of Antibacterial, Mechanical, and Structural Properties of Polyvinyl Chloride\\/Silver Nitrate Composites Prepared by Thermoplastic Compounding
Polyvinyl chloride\\/silver nitrate composites were prepared by thermoplastic compounding. Antibacterial activity against gram-negative and gram-positive bacteria was determined by agar diffusion test. X-ray diffraction, X-ray photoelectron spectroscopy, and optical microscopy analyses were carried out to determine the effect of polyvinyl chloride modification on structural properties. The mechanical characteristics of prepared films were observed using stress-strain analysis. The results revealed that
Martha Merchan; Jana Sedlarikova; Alenka Vesel; Vladimir Sedlarik; Miroslav Pastorek; Petr Sßha
Acetate absorption in the normal and secreting rat jejunum.
Acetate absorption was studied in rat jejunum using steady state perfusion in vivo. Absorption conformed to apparent saturation kinetics and was similar in magnitude to glucose absorption. When compared with normal saline, acetate perfusion was associated with luminal alkalinisation. There was no difference in total CO2 secretion when similar rates of acetate and glucose absorption were compared, suggesting that total CO2 secretion was the result of mucosal metabolism. Absorption of acetate and propionate were mutually inhibitory. Acetate absorption was also inhibited by Tris-Hepes pH 7.0. When the gut was pretreated with cholera toxin to induce a secretory state, acetate absorption was reduced by 41.9%. This effect could be reproduced if similar water secretion was osmotically induced by the addition of mannitol. These data suggest that acetate is absorbed, at least, partially by non-ionic diffusion in the rat jejunum and that its absorption is reduced in the secreting intestine by solvent drag.
Watson, A J; Elliott, E J; Rolston, D D; Borodo, M M; Farthing, M J; Fairclough, P D
Electrical and spectroscopic characterization of polyaniline polyvinyl chloride (PANI PVC) blends doped with sodium thiosulphate
Polyaniline is doped with sodium thiosulphate in aqueous tetrahydrofuran (THF) and the blended films have been prepared by changing the amount of doped polyaniline (PANI) in the fixed amount of polyvinyl chloride (PVC). The electrical conductivity of various samples of polyaniline-polyvinyl chloride (PANI-PVC) blends has been studied to see the effect of dopant in the temperature range 300-400 K. Mott's parameters are used to explain the conduction mechanism. Different parameters such as pre-exponential factor ( ?0), activation energy (? E) and T0 have also been calculated to see the effect of chemical doping. The crystallinity of the blends is explained on the basis of T0. The calculated values of T0 show that crystallinity increases with an increase of doped PANI in PANI-PVC blends. Fourier transform-infrared (FTIR) spectroscopy is done to explore the nature and interaction of dopant into the polymeric chain.
Ameen, Sadia; Ali, Vazid; Zulfequar, M.; Mazharul Haq, M.; Husain, M.
Synthesis and characterization of polyvinyl alcohol based multiwalled carbon nanotube nanocomposites
Multiwalled carbon nanotubes were synthesized by chemical vapor deposition over an Fe-Co/alumina catalyst. Nanotubes were then oxidized and grafted with polyvinyl alcohol (PVA). The obtained nanostructure was characterized by Raman spectroscopy, XRD, FTIR, EDX, SEM, TEM and TGA methods. FTIR confirmed the presence of the characteristic peaks of the anticipated ester group. The formation of polymer nanocomposites based on polyvinyl alcohol and multiwalled carbon nanotubes was confirmed by SEM and TEM. High resolution electron micrographs revealed that the primary binding sites for PVA grafting are the sidewall defects of the nanotubes. The novelty of this work is the use of the Fischer esterification reaction for creating the permanent link between the nanotubes and the PVA matrix.
Malikov, E. Y.; Muradov, M. B.; Akperov, O. H.; Eyvazova, G. M.; Puskßs, R.; Madarßsz, D.; Nagy, L.; Kukovecz, ┴.; K¾nya, Z.
Surface vibrational spectroscopic studies of rubbed polyvinyl cinnamate for liquid crystal alignment
The critical role of buffing strength of poly(vinyl cinnamate) (PVCi) surface for liquid crystal (LC) alignment is reported. It has been found that weakly and strongly rubbed PVCi films provide LC alignment which is perpendicular and parallel to the rubbing direction, respectively. Surface-specific sum-frequency vibrational spectroscopy have been used to investigate the structure of poly(vinyl cinnamate) (PVCi) surface on a molecular level. Quantitative analysis provides an approximate orientation distribution function (ODF) for the aligned cinnamate moieties and the polymer backbones. Weak rubbing aligns the phenyl ring of the cinnamate side-chains perpendicular to the rubbing direction, with the main axis along the surface normal. Strong rubbing orients the phenyl rings toward the plane normal to the surface along the rubbing direction.
Pagliusi, P.; Chen, C. Y.; Shen, Y. R.
Polyvinyl alcohol-coated hybrid fiber grating for relative humidity sensing.
A relative humidity (RH) sensor based on a hybrid fiber grating coated with polyvinyl alcohol is proposed and demonstrated experimentally. The hybrid fiber grating is formed by superimposing a normal fiber Bragg grating (FBG) and a tilted-FBG around the same position of a single-mode fiber so that it can work in the reflection mode. Optical power of the reflected signal changes with the refractive index of the moisture sensitive polyvinyl alcohol, and humidity measurement can be realized. Experimental results show that the measurement range is 30 to 95% with the maximum sensitivity of 0.737 nW?% RH. The average response time is ?2 s and the measurement is nearly insensitive to temperature. Compared with the wavelength detection method used in normal FBG-based relative humidity sensors, the intensity demodulation method in this report is simpler and more cost-efficient. PMID:21806281
Dong, Xinyong; Li, Tao; Liu, Yang; Li, Yi; Zhao, Chun-Liu; Chan, Chi Chiu
Reversible energy transfer between monomers and fluorescent dimers of rhodamine S in polyvinyl alcohol films
Nonradiative energy transfer and excitation trapping are studied for rhodamine S in polyvinyl alcohol (PVA) films. It occurs that fluorescent dimers of rhodamine S can play a role of imperfect traps for the excitation energy. At highest dye concentrations experimental data of fluorescence quantum yield and emission anisotropy cannot be described by the model of energy transfer neglecting the possibility of excitation return to the monomers. However, the agreement between experimental data and the results of computations can be much improved, if the reverse energy transfer is taken into account. Based on the quantitative analysis it is possible to estimate selected characteristics of rhodamine S dimer in polyvinyl alcohol matrix. The experiments and corresponding analysis are made both at room and elevated temperature.
Synak, A.; Ku?ak, L.; Range?owa-Jankowska, S.; Grobelna, B.; Kubicki, A.; Bojarski, P.
Bonding, vibrational, and electrical characteristics of CdS nanostructures embedded in polyvinyl alcohol matrix
CdS nanocomposites have been grown in polyvinyl alcohol matrix by a chemical synthesis process. The transmission electron micrographs of nanocomposites synthesized at 70-90 ░C temperature showed the growth of needlelike and junctionlike nanostructures. X-ray photoelectron spectroscopy analysis revealed the growth of stoichiometric CdS without the formation of any intermediate phases at the CdS-polyvinyl alcohol interface. Raman spectra of first order longitudinal optical phonon peak has been analyzed using phonon dispersion model to detect the surface phonon modes in CdS nanoneedles and wires. The origin of negative differential resistance behavior in current-voltage characteristics for junctionlike CdS nanocomposites has been discussed.
Mondal, S. P.; Dhar, A.; Ray, S. K.; Chakraborty, A. K.
The investigation of the degradation mechanism from the kinetic parameters of dehydrochlorinated polyvinyl chloride decomposition
Kinetic theory in regards to the basic understanding of reaction order as it relates to polymer degradation is discussed. The theory is then tested by determining the kinetic parameters for dehydrochlorinated polyvinyl chloride using thermogravimetric analysis. Four different mechanisms of degradation were deduced from four sets of kinetic parameters. The calculated kinetic parameters were apparent reaction order, apparent activation energy, and apparent frequency factor as determined by the original Freeman and Carroll model. A method for obtaining the optimal heating rate from a set of heating rates is also discussed. The product distributions for polyvinyl chloride, polyethylene, polypropylene, and polystyrene are also discussed. When the product distributions are separated into two divisions (volatile and non-volatile) two different modes of degradation are observed for each polymer. The non-volatile product distribution is characterized by random chain scission kinetics while the volatile product distribution is either controlled by some other kinetic phenomenon, thermodynamically controlled, or a combination of the two.
Jordan, Kelly Joel
Calcium Magnesium Acetate at Lower-Production Cost: Production of CMA Deicer from Cheese Whey.
Calcium magnesium acetate (CMA), a mixture of calcium acetate and magnesium acetate, is used as an environmentally benign roadway deicer. The present commercial CMA deicer made from glacial acetic acid and dolomitic lime or limestone is expensive compared...
H. Zhu S. T. Yang W. Qin Y. Huang Y. L. Huang Z. Jin
Release behavior of tanshinone IIA sustained-release pellets based on crack formation theory.
The objective of this study was to investigate the drug release mechanism and in vivo performance of Tanshinone IIA sustained-release pellets, coated with blends of polyvinyl acetate (PVAc) and poly(vinyl alcohol)-poly(ethylene glycol) (PVA-PEG) graft copolymer. A formulation screening study showed that pellets coated with PVAc-PVA-PEG at a ratio of 70:30 (w/w) succeeded in achieving a 24 h sustained release, irrespective of the coating weight (from 2% to 10%). Both the microscopic observation and mathematical model gave further insight into the underlying release mechanism, indicating that diffusion through water-filled cracks was dominant for the control of drug release. In vivo test showed that the maximum plasma concentration of sustained-release pellets was decreased from 82.13 ▒ 17.05 to 40.50 ▒ 11.72 ng mL as that of quick-release pellets. The time of maximum concentration, half time, and mean residence time were all prolonged from 3.80 ▒ 0.40 to 8.02 ▒ 0.81 h, 4.28 ▒ 1.21 to 8.18 ▒ 2.06 h, and 8.60 ▒ 1.59 to 17.50 ▒ 2.78 h, compared with uncoated preparations. A good in vitro-in vivo correlation was characterized by a high coefficient of determination (r = 0.9772). In conclusion, pellets coated with PVAc-PVA-PEG could achieve a satisfactory sustained-release behavior based on crack formation theory. PMID:22610467
Liu, Pan; Li, Jin; Liu, Jianping; Yang, Jikun; Fan, Yongqing
Microstructure and free volume evaluation of poly(vinyl alcohol) nanocomposite hydrogels
A new type of organic\\/inorganic nanocomposite hydrogel was prepared by introducing small amount of natural montmorillonite (MOM) into a poly(vinyl alcohol) (PVA)\\/sulfonated polyester (PES) system. The crystalline structure and crystallinity degree were determined by differential scanning calorimetry (DSC) and wide angle X-ray spectroscopy (WAXS). The presence of PES leads to an increase in the crystallinity degree of the PVA matrix
Caio M. Paranhos; Bluma G. Soares; Josķ C. Machado; Dario Windm÷ller; Luiz A. Pessan
Structure and Properties of Poly(vinyl chloride)\\/Halloysite Nanotubes Nanocomposites
Poly(vinyl chloride)(PVC)\\/halloysite nanotubes (HNTs) nanocomposites were prepared by melt blending. The effects of HNT content on the mechanical properties, morphology, and rheological properties of the nanocomposites were investigated. The results showed that HNTs were effective in toughening and reinforcing PVC nanocomposites. The notched impact, tensile and flexural strength, and flexural modulus of the nanocomposites were remarkably increased compared with those
Application of electrochemically prepared polypyrrole¢polyvinyl sulphonate films to DNA biosensor
Double stranded calf thymus deoxyribonucleic acid (DNA) was physisorbed onto polypyrrole¢polyvinyl sulphonate (PPY¢PVS) films electrochemically deposited onto indium¢tin¢oxide (ITO) coated glass plates. These DNA immobilized PPY¢PVS films optimized for various conditions, such as polymerization potential, pH of buffer, DNA concentration and scan rate were characterized using Fourier-transform infrared (FT-IR) spectroscopy, atomic force microscopy (AFM) and cyclic voltammetry (CV) techniques, respectively.
Kavita Arora; Asha Chaubey; Rahul Singhal; Ravindra P. Singh; M. K. Pandey; S. B. Samanta; B. D. Malhotra; Subhash Chand
Decoupled ion conduction mechanism of poly(vinyl alcohol) based Mg-conducting solid polymer electrolyte
Investigation on solid state rechargeable magnesium batteries are considered important similar to lithium batteries. In view of negligible hazard and less reactivity of the magnesium, in comparison with lithium, studies on rechargeable magnesium batteries are expected to have a wide scope in future. In the present investigations, decoupled ion conduction of poly(vinyl alcohol) (PVA)-based Mg-conducting solid polymer electrolytes (SPEs) is
Soo-Kyeong Jeong; Yun-Kyung Jo; Nam-Ju Jo
Crystallization behavior of melt-spun poly(vinyl alcohol) fibers during drawing process
The crystallization behavior of melt-spun poly(vinyl alcohol) (PVA) fibers during hot drawing process was studied by differential\\u000a scanning calorimetry (DSC), X-ray diffraction (XRD) and computer controlled electronic universal testing machine. The effects\\u000a of drawing temperature and drawing speed on the crystallinity and the stress induced crystallization of PVA fibers were discussed.\\u000a The results showed that the crystallization process of PVA
Qian Wu; Ning Chen; Qi Wang
Electrical conduction mechanism of polyvinyl chloride (PVC)-polymethyl methacrylate (PMMA) blend film
The electrical conduction mechanism in polyvinyl chloride (PVC)--polymethyl methacrylate (PMMA) blend film has been studied at various temperatures in the range 313 K to 353 K. The results are presented in the form of I--V characteristics. Analysis has been made in the light of Poole-Frenkel, Fowler--Nordheim, Schottky, log(J) vs. T plots and Arrhenius plots. It is observed that, Schottky-Richardson mechanism is primarily responsible for the observed conduction.
Gulalkari, R. S.; Bakale, Y. G.; Burghate, D. K.; Deogaonkar, V. S.
Electrospun single-walled carbon nanotube\\/polyvinyl alcohol composite nanofibers: structure property relationships
Polyvinyl alcohol (PVA) nanofibers and single-walled carbon nanotube (SWNT)\\/PVA composite nanofibers have been produced by electrospinning. An apparent increase in the PVA crystallinity with a concomitant change in its main crystalline phase and a reduction in the crystalline domain size were observed in the SWNT\\/PVA composite nanofibers, indicating the occurrence of a SWNT-induced nucleation crystallization of the PVA phase. Both
Minoo Naebe; Tong Lin; Mark P. Staiger; Liming Dai; Xungai Wang
Synthesis and characterization of polyvinyl alcohol\\/nanospherical cellulose particle films
A procedure for synthesizing cellulose nanospheres with size of 5.9 and 10.9nm for cotton linter and linen, respectively, was developed. A series of polyvinyl alcohol (PVA)\\/nano-cellulose films were cast. Mechanical, biodegradation and scanning electron micrograph (SEM) of nano-cellulose-filled PVA films were studied. With the addition of 20% nano-cellulose from linen there was an increase in the tensile strength and percentage
Maha M. Ibrahim; Waleed K. El-Zawawy; Mona A. Nassar
Influence of polymer additives on thermal decomposition and smoke emission of poly(vinyl chloride)
The influence of polymer additives and metal oxides on thermal decomposition and smoke suppression of poly(vinyl chloride) was investigated using a cone calorimeter at an incident heat flux of 25 kW m?2. Acrylate (acrylic K120N), chlorinated polyethylene, PVC-MC100 and polyethylene wax were used as polymer additives, and metal oxides including CuO, MoO3 and FeOOH as smoke suppressants. The experimental data
Bin Li
Small angle neutron scattering by interpenetrating polymer networks of poly(carbonate-urethane) and polyvinyl pyridine
Small-angle neutron scattering experiments by interpenetrating networks of poly(carbonate-urethane) and polyvinyl pyridine reveal that there is some degree of microphase separation at all composition at all compositions, possibly, in some compositions, into a bicontinuous phase. The domain size is some undred angstr÷ms in the samples with only one one glass transition temperature, and is much smaller than the domain size for samples with two glass temperatures.
Brulet, A.; Daoud, M.; Zhou, P.; Frisch, H. L.
Dielectric Relaxation and Compatibility Investigation of Polystyrene\\/Polyvinyl Chloride Blends
A systematic dielectric study over a frequency range 100ĀHz up to 100ĀkHz was carried out on polystyrene\\/polyvinyl chloride (PS\\/PVC) blends with different concentrations of maleic anhydride (MA) ranging from 0¢20%. After subtraction of the losses resulting from DC conductivity, the dielectric data were fitted in the frequency domain by two Fr÷hlich regions. The first absorption region in the lower frequency
S. L. Abd-El-Messieh
The improvement of mechanical properties of spruce galactogluco- mannan (GGM)-based films was sought by blending GGM with each of poly(vinyl alcohol) (PVOH), corn arabinoxylan (cAX), and konjac glucomannan (KGM). The blend ratios were 3:1, 1:1, and 1:3 (w\\/w), and in addition films were made from each of the polymers alone. Glycerol was used as plasticizer. Adding other polymers increased the
Kirsi S. Mikkonen; Madhav P. Yadav; Peter Cooke; Stefan Willf÷r; Kevin B. Hicks; Maija Tenkanena
The kinetic parameters for the evaporation of plasticizers from plasticized poly(vinyl chloride)
The process of loss of plasticizers: dioctyl phthalate, diisononyl phthalate, benzylbutyl phthalate, dioctyl adipate, phosphate plasticizer Reofos, polymeric plasticizer Reoplex and epoxidized soybean oil from plasticized poly(vinyl chloride) folies was studied by the method of isothermal thermogravimetry in the temperature range 120¢150░C. The investigated samples contained ca. 10¢40wt.% of plasticizers. The rate constants of the process of loss of plasticizers
Tonka Kova?i?; Äeljko Mrkli?
Highly isotactic poly(vinyl alcohol). III: Heterogeneous cationic polymerization of tert-butyl vinyl ether
We studied the polymerization of tert-butyl vinyl ether (tBVE) and benzyl vinyl ether with heterogeneous catalysts, that is, modified Ziegler type (Vandenberg type) catalysts and metal sulfate¢sulfuric acid complexes.Vandenberg type catalysts gave high molecular weight and highly isotactic poly(tBVE)s with relatively narrow molecular weight distribution at high temperature, and then the resultant poly(tBVE)s were converted into the stereoregular poly(vinyl alcohol)s
Hiroyuki Ohgi; Toshiaki Sato
Conductivity measurement of poly(vinyl borate) and its lithium derivative in solid state
Poly(vinyl borate), PVBO and lithium derivative of PVBO can be prepared by homogeneous esterification of PVA with boric acid in non-aqueous medium in the presence of a catalyst C2H5ONO2ĘDMSO. The compounds were characterised by IR and 1H NMR spectra. Conductivities were determined from 30 to 90░C in solid state. The compounds so formed showed ionic conductivity and their conductivities were
Prafulla Chetri; Narendra N. Dass; Neelotpal Sen Sarma
High-dose film dosimeters based on bromophenol blue or xylenol orange dyed polyvinyl alcohol
Dyed poly(vinyl alcohol) (PVA) films, prepared by a simple technique of casting acqueous solutions of PVA containing bromophenol blue (BPB) or xylenol orange (XYO) on a horizontal glass plate, are useful as routine high-dose dosimeters. These flexible plastic film dosimeters are bleached when exposed to ?-ray photons. Absorbed doses should not exceed 20 kGy for BPB\\/PVA film and 90 kGy
A. A. Abdel-Fattah; S. Ebraheem; M. El-Kelany; F. Abdel-Rehim
Preparation of poly(vinyl alcohol) hydrogels containing citric or succinic acid using gamma radiation
Ternary mixtures of poly(vinyl alcohol) (PVA)\\/citric acid (CA)\\/water and PVA\\/succinic acid (SA)\\/water were exposed to various gamma doses in air at ambient temperature. The maximum swelling and the gelation% of the prepared gels initially increases with increasing dose for both acids, but at higher doses decreases. The uptake of nickel and cobalt ions increases with increasing bonded acid concentration, which
Zaki Ajji
Evaluation of microstructure and photochromic behavior of polyvinyl alcohol nanocomposite films containing polyoxometalates
A series of photochromic nanocomposite films were prepared by well-dispersed Keggin type polyoxometalates (POM) in polyvinyl alcohol (PVA). The corresponding structure, photochromic behaviors and mechanism of the films were investigated with transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared spectra (FT-IR), ultraviolet visible absorption spectra (UV¢vis) and electron resonance spectra (ESR). In composite films, the sphere-shaped POM
Li-Mei Ai; Wei Feng; Jie Chen; Yan Liu; Wei-min Cai
Stabilizing effect of epoxidized sunflower oil on the thermal degradation of poly(vinyl chloride)
Unsaturated triglyceride oil (sunflower) was obtained from commercial sources. It was epoxidized and characterized by chemical and spectroscopic methods. The thermo-oxidative degradation of poly(vinyl chloride) at 180Ā░C was investigated. The effects of different metal carboxylate combinations (Ba\\/Cd and Ca\\/Zn stearates) in the presence of epoxidized sunflower oil on static heat treatment of PVC have been studied. In order to compare
M. T Benaniba; N Belhaneche-Bensemra; G Gelbard
Polysiloxane¢polyvinyl alcohol discs as support for antibody immobilization: Ultrastructural and physical¢chemical characterization
A semi-interpenetrated polymer network of posiloxane and polyvinyl alcohol (POS¢PVA) was synthesized through sol¢gel process in the form of discs and used as solid support for antibody immobilization. POS¢PVA discs presented a protein loading capacity of approximately 210?g\\/disc and can covalently bind an anti-S100 protein antibody via glutaraldehyde. The POS¢PVA matrix network resulted in hard and spherical discs of uniform
Mario Ribeiro de Melo-Junior; Luiz Carlos Alves; Fßbio Brayner dos Santos; Eduardo Isidoro Carneiro BeltrŃo; Luiz Bezerra de Carvalho Jr.
Preparation and characterization of poly(vinyl chloride) calcium carbonate nanocomposites via melt intercalation
Calcium carbonate was synthesized by inĀsitu deposition technique and its nano size (35¢60Ānm) was confirmed by transmission\\u000a electron microscopy (TEM). Composites of the filler CaCO3 (micro and nano) and the matrix poly(vinyl chloride) (PVC) were prepared with different filler loadings (0¢5Āwt%) by melt\\u000a intercalation. Brabender torque rheometer equipped with an internal mixer has been used for preparation of formulations for
C. B. Patil; U. R. Kapadi; D. G. Hundiwale; P. P. Mahulikar
Polyvinyl butyral films containing leuco-malachite green as low-dose dosimeters
Thin films containing leuco-malachite green (LMG) dye in polyvinyl butyral (PVB) have been developed for dose measurements of a few hundreds Gy level. The film shows significant color change in the visible range, and the sensitivity of the film to absorbed dose was enhanced by addition of chloride-containing compounds, such as chloral hydrate or 2,2,2-trichloroethanol. The film is suitable as dosimeters for dose measurements, e.g. in food irradiation and environmental protection.
Mai, Hoang Hoa; Solomon, H. M.; Taguchi, M.; Kojima, T.
Dielectric and transport properties of carbon nanotube-CdS nanostructures embedded in polyvinyl alcohol matrix
Multiwalled carbon nanotube-CdS\\/polyvinyl alcohol (MWCNT-CdS\\/PVA) composites have been grown by a simple chemical process on one-dimensional templates. The plane-view transmission electron micrographs clearly indicate the formation of nanocrystalline CdS on the nanotube surfaces. The superior dielectric behavior of the MWCNT-CdS nanostructures over MWCNT and PVA host matrices has been demonstrated. The dc and ac transport properties of CdS carbon nanotube-insulating
S. P. Mondal; R. Aluguri; S. K. Ray
Synthesis and Characterization of Poly(vinyl alcohol) Membranes with Quaternary Ammonium Groups for Wound Dressing
2-[(acryloyloxy)ethyl]Trimethylammonium chloride (AETMAC) was grafted onto poly(vinyl alcohol) (PVA) using ceric ammonium nitrate (CAN) as a redox initiator. A series of graft co-polymer (PVA-g-PAETMAC) membranes with different contents of AETMAC were prepared with a casting method. The incorporation of AETMAC into PVA chains was confirmed by element analysis and Fourier transform infrared spectroscopy. The effects of grafting on the thermal
Kuo-Yu Chen; Yu-Sheng Lin; Chun-Hsu Yao; Ming-Hsien Li; Jui-Che Lin
Film dosimeters based on methylene blue and methyl orange in polyvinyl alcohol
Polyvinyl alcohol (PVA) films containing methylene blue and methyl orange are useful as gamma and electron radiation dosimeters. Absorbed doses should not exceed 40 kGy for methylene blue and 500 kGy for methyl orange. Because PVA is water-soluble, the films may be made without toxic solvents. The effects of irradiation temperature and humidity on the radiation response of the dosimeter films are discussed.
Chung, W.H. (Pusan National Univ. (Korea, Republic of). Dept. of Physics); Miller, A. (Risoe National Lab., Roskilde (Denmark))
Improvement of an enzyme electrode by poly(vinyl alcohol) coating for amperometric measurement of phenol
A poly(vinyl alcohol) film cross-linked with glutaraldehyde (PVA¢GA) was introduced to the surface of a tyrosinase-based carbon paste electrode. The coated PVA¢GA film was beneficial in terms of increasing the stability and reproducibility of the enzyme electrode. The electrode showed a sensitive current response to the reduction of the o-quinone, which was the oxidation product of phenol, by the tyrosinase,
Gha-Young Kim; Nguyen Manh Cuong; Seung-Hee Cho; Joonmok Shim; Jung-Je Woo; Seung-Hyeon Moon
Heat-Induced Evolution of the Mesoscopic Structure of Dehydrated Poly(vinyl alcohol) Gel
Time-resolved small-angle X-ray scattering (SAXS) investigations were carried out in order to clarify the heat treatment effects on the structure of a dehydrated substance made from a crystalline-polymer (poly(vinyl alcohol)) hydrogel. The heat-treatments performed in the present study consisted of two procedures: an initial temperature increase to a target temperature (Tt) and a successive thermoregulation to maintain Tt. The evolution
Masaaki Sugiyama; Masahiko Annaka; Kazuhiro Hara
Nanoporous Nanocomposite Hydrogels Composed of Polyvinyl Alcohol and Na-montmorillonite
Polyvinyl alcohol nanoporous nanocomposite hydrogels containing various levels of Na-montmorillonite were prepared by a cyclic freezing-thawing technique. An exfoliated morphology of silicate layers was observed for the nanocomposite hydrogels. The uniaxial tensile test indicated that the tensile modulus and tensile strength of the nanocomposite hydrogels increased with increasing Na-montmorillonite content, while their elongation-at-break values decreased. The results showed that by
Analysis of phthalic acid diesters, monoester, and other plasticizers in polyvinyl chloride household products in Japan
The aim of this study was to determine the concentrations of six phthalic acid diesters (PAEs) [di(2-ethylhexyl) phthalate (DEHP), di-n-butyl phthalate (DBP), butyl benzyl phthalate (BBP), diisononyl phthalate (DINP), di-n-octyl phthalate (DNOP), and diisodecyl phthalate (DIDP)], two non-phthalic plasticizers [di(2-ethylhexyl) adipate (DEHA), 2,2,4-trimethyl-1,3-pentanediol diisobutylate (TMPDIB)], and mono 2-ethylhexyl phthalate(MEHP) in polyvinyl chloride (PVC) household products that children often places in
Tsuyoshi Kawakami; Kazuo Isama; Atsuko Matsuoka
Isolation of new and potent poly(vinyl alcohol)-degrading strains and their degradation activity
Poly(vinyl alcohol) (PVA)-degrading bacteria were isolated from various sources such as activated sludge from the watercourse of textile and dyeing factories, cultivating soil and leaf mold. Acclimation of the isolated strains enhanced the PVA degradation activity by 1.3¢1.7 times. Cardiobacterium sp. SB68 (SB68) and an unidentified bacterium (SB69) degraded PVA through symbiotic interactions. In contrast, Achromobacter cholinophagum SB98 (SB98) degraded
Jea-An Lee; Mal-Nam Kim
Study on poly(vinyl alcohol)\\/carboxymethyl-chitosan blend film as local drug delivery system
The distinguishable films composed of poly(vinyl alcohol) (PVA) and carboxymethyl-chitosan (CMCS) were prepared by blending\\/casting\\u000a method, and loaded with ornidazole (OD) as local drug delivery system. In vitro test, the blend films showed pH-responsive\\u000a swelling behavior and moderate drug release action, and also exhibited a little antimicrobial activity against E. coli and S. aureus strains. Those characteristics of CMCS\\/PVA blend
Ling-Chong Wang; Xi-Guang Chen; De-Yu Zhong; Quan-Chen Xu
Radiation synthesis and characterization of stimuli-sensitive chitosan-polyvinyl pyrrolidone hydrogels
Novel cationic hydrogels were synthesized by gamma-irradiation copolymerization of chitosan and polyvinyl pyrrolidone (PVP). The synthesis regularities and the swelling behaviour of hydrogels have been studied. It was shown that increasing of PVP concentration in feed composition also as radiation dose accompanied of increase of yield of gel fraction and decrease of swelling degree. At dose more than 3.5kGy increasing
Sergey A. Dergunov; Irina K. Nam; Grigoriy A. Mun; Zauresh S. Nurkeeva; Erengaip M. Shaikhutdinov
Radiation synthesis and characterization of stimuli-sensitive chitosan¢polyvinyl pyrrolidone hydrogels
Novel cationic hydrogels were synthesized by ?-irradiation copolymerization of chitosan and polyvinyl pyrrolidone (PVP). The synthesis regularities and the swelling behaviour of hydrogels have been studied. It was shown that increasing of PVP concentration in feed composition also as radiation dose accompanied of increase of yield of gel fraction and decrease of swelling degree. At dose more than 3.5kGy increasing
?-irradiated chitosan-polyvinyl pyrrolidone hydrogels as pH-sensitive protein delivery system
The effects of pH of the buffer solution and the composition of the hydrogel system on the bovine serum albumin (BSA) adsorption capacity of chitosan (CS)¢polyvinyl pyrrolidone (PVP) (CSPVP) hydrogels and release of BSA were investigated. Poly-electrolyte CSPVP hydrogels with different compositions were prepared by irradiating CS\\/PVP\\/water mixtures with ?-rays at ambient temperature. The adsorption capacity of hydrogels was found
Sergey A. Dergunov; Grigoriy A. Mun
gamma-irradiated chitosan-polyvinyl pyrrolidone hydrogels as pH-sensitive protein delivery system
The effects of pH of the buffer solution and the composition of the hydrogel system on the bovine serum albumin (BSA) adsorption capacity of chitosan (CS) polyvinyl pyrrolidone (PVP) (CSPVP) hydrogels and release of BSA were investigated. Poly-electrolyte CSPVP hydrogels with different compositions were prepared by irradiating CS\\/PVP\\/water mixtures with gamma-rays at ambient temperature. The adsorption capacity of hydrogels was
Studies of the interaction of polyvinyl pyrrolidone with reduced vat dyes using visible spectroscopy
Interaction between polyvinyl pyrrolidone (PVP) and the reduced form of two anthraquinone vat dyes has been studied using the results of spectrophotometric measurements. These results indicate that different types of interaction are possible depending on the chemical constitution of the vat dye and the amount of PVP. Comparison has been made between this interaction behaviour and that which occurs between anions of a disazo dye and PVP under neutral and alkaline conditions.
Sheth, Geeta N.
Thermal and Morphological Properties of Poly(vinyl alcohol) and Layered Double Hydroxide (LDH) Nanocomposites
Poly(vinyl alcohol) (PVA)\\/layered double hydroxide (LDH) nanocomposites were synthesized with different compositions: 0, 2, 4, 6, and 8Āwt% of LDH by the solution intercalation method. The effects of the layered double hydroxide platelet concentration on the properties of the PVA\\/LDH films were investigated by thermogravimetric analysis (TGA), optical microscopy, and Fourier transform infrared spectroscopy (FTIR). A reduction in the onset
B. Ramaraj; S. N. Jaisankar
Linear dichroism study of 9-substituted acridines in stretched poly(vinyl alcohol) film
Polarized absorption spectra have been measured on acridine, acridone and the 9-aminoacridinium and 9-amino-10-methylacridinium cations in stretched poly(vinyl alcohol) films, in the absorption region 220-500 nm, and corresponding transition moment directions were determined. The acridine derivatives should be suitable as bio-structural probes, as they provide transitions which are polarized exactly parallel to the two symmetry axes in the molecular plane.
Matsuoka, Yukio; Nordķn, Bengt
Structure of oriented fibers based on poly(vinyl alcohol) modified by detonation nanodiamonds
A comparative study of the structure and mechanical and thermal characteristics of nanocomposite oriented fibers based on\\u000a poly(vinyl alcohol) impregnated with the nanodiamonds prepared by detonation synthesis and fibers based on the initial unmodified\\u000a polymer has been performed. The conditions and regimes of gel spinning of the nanocomposite fibers containing highly dispersed\\u000a nanosized filler without its aggregation are defined. The
T. S. Kurkin; A. N. Ozerin; A. S. KechekÆyan; L. A. Ozerina; E. S. Obolonkova; M. A. Beshenko; V. Yu. Dolmatov
Synthesis and release studies of oil-containing poly(vinyl alcohol) microcapsules prepared by coacervation
Oil-containing poly(vinyl alcohol) (PVA) microcapsules were prepared by the simple coacervation method followed by the chemical cross-linking of the coacervated PVA membrane with glutaraldehyde. The effect of various parameters such as the microcapsule size, the degree of cross-linking of the coacervated polymer membrane, the amount of the desolvating agent, the surfactant concentration and the ionic strength of the aqueous release
Aristi R. Bachtsi; Costas Kiparissides
Single wall carbon nanotube templated oriented crystallization of poly(vinyl alcohol)
Shearing of poly(vinyl alcohol) (PVA)\\/single wall carbon nanotube (SWNT) dispersions result in the formation of self-assembled oriented PVA\\/SWNT fibers or ribbons, while PVA solution results in the formation of unoriented fibers. Diameter\\/width and length of these self-assembled fibers was 5¢45?m and 0.5¢3mm, respectively. High-resolution transmission electron micrographs showed well resolved PVA (200) lattice with molecules oriented parallel to the nanotube
Marilyn L. Minus; Han Gi Chae; Satish Kumar
Preparation and characterization of poly(vinyl sulfone)- and poly(vinylidene fluoride)-based electrolytes
A novel group of polymer electrolytes based on poly(vinyl sulfone) (PVS) and poly(vinylidene fluoride) (PVdF) polymers, plasticized with highly conductive solutions of LiClO4, LiN(CF3SO2)2 or LiAsF6 dissolved in ethylene carbonate, propylene carbonate, sulfolane, or mixtures thereof, was prepared via in situ photopolymerization and solution casting, respectively. The polymer electrolytes were characterized from conductivity and cyclic voltammetry data. It was found
H. S. Choe; J. Giaccai; M. Alamgir; K. M. Abraham
Assessing biodegradability of plastics based on poly(vinyl alcohol) and protein wastes
Research was conducted into biodegradability of mixed polymer films based on poly(vinyl alcohol), protein hydrolyzate (collagen hydrolyzate from wastes after chrome tanning) and glycerol in an aqueous aerobic environment. Evaluation of biodegradation was based on carbon dioxide produced in the gas phase. Pure PVAL was degraded by a current mixed culture for water-treatment (unadapted) only after an approx. 10-day lag
Jarom??r Hoffmann; Iveta ?ezn???kovß; Jarmila Kozßkovß; Jan R?×i?ka; Pavol Alexy; DuÜan BakoÜ; Lenka Precnerovß
Investigation into Stability of Poly(Vinyl Alcohol)Based Opadry« II Films
Poly(vinyl alcohol) (PVA)-based formulations are used for pharmaceutical tablet coating with numerous advantages. Our objective\\u000a is to study the stability of PVA-based coating films in the presence of acidic additives, alkaline additives, and various\\u000a common impurities typically found in tablet formulations. Opadry« II 85F was used as the model PVA-based coating formulation.\\u000a The additives and impurities were incorporated into the
Otilia M. Y. Koo; John D. Fiske; Haitao Yang; Faranak Nikfar; Ajit Thakur; Barry Scheer; Monica L. Adams
Vinyl chloride and polyvinyl chloride: Toxicology. (Latest citations from the Life Sciences Collection database). Published Search
The bibliography contains citations concerning the toxicity of vinyl chloride and polyvinyl chloride following short- and long-term exposure. The citations explore how these compounds are metabolized and consider their carcinogenic and teratogenetic potential. Methodologies to quantitate their presence in atmospheric dust and body tissues are discussed. Occupational hazards are also noted.(Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)
Thermal degradation of poly(vinyl butyral) in alumina, mullite and silica composites
Thermal degradation of poly(vinyl butyral) (PVB) and its mixtures with alumina, mullite and silica was investigated by non-isothermal thermogravimetry in the temperature range of 323 to 1273 K. The analysis of the data was carried out using a three-dimensional diffusion model. Results showed that the kinetic parameters (activation energy and pre-exponential factor) of the PVB degradation are different for polymer
T. C. K. Yang; W. H. Chang; D. S. Viswanath
Modification of poly(vinyl butyral) coatings using bis-silanes
A commercially available poly(vinyl butyral) (PVB) coating was modified using a combination of 1¢10wt.% bis(trimethoxysilylethyl)benzene and dibutyltin dilaurate as the hydrolysis catalyst. Results of attenuated total reflectance (ATR)¢FTIR analysis indicated the modification resulted in a hybrid coating material containing silicate moieties covalently bonded to the PVB polymer chains. Gravimetric analysis indicted the bis-silane addition resulted in a reduction in the
Tammy L. Metroke; Michael V. Henley
Electrical behavior of polymer hydrogel composed of poly(vinyl alcohol)¢hyaluronic acid in solution
Interpenetrating polymer networks (IPN), as polymer hydrogels composed of poly(vinyl alcohol) (PVA) and hyaluronic acid (HA), which exhibited electrical sensitive behavior were prepared. The swelling behavior of the IPN\\/HA IPN was studied by immersing the gel in various concentrations of aqueous NaCl solutions and various pH buffer solutions. The response of the PVA\\/HA IPN to electric fields stimuli was also
Seon Jeong Kim; Seoung Gil Yoon; Young Moo Lee; Hee Chan Kim; Sun I. Kim
Swelling behavior of interpenetrating polymer network hydrogels composed of poly(vinyl alcohol) and chitosan
Interpenetrating polymer network (IPN) hydrogels composed of poly(vinyl alcohol) (PVA) and chitosan were prepared by UV irradiation. The characteristics of IPN hydrogels were investigated by swelling experiments, Fourier transform infrared (FT-IR) spectroscopy and differential scanning calorimetry (DSC). IPN hydrogels exhibited a relatively high swelling ratio in the range of 210¢350% at 35░C. The swelling ratio of PVA\\/chitosan IPN hydrogels depended
Seon Jeong Kim; Sang Jun Park; Sun I. Kim
Electrical sensitive behavior of poly(vinyl alcohol)\\/poly (diallyldimethylammonium chloride) IPN hydrogel
Interpenetrating polymer network (IPN) hydrogel composed of poly(vinyl alcohol) (PVA) and poly(diallyldimethylammonium chloride) (PDADMAC) exhibited electrical-sensitive behavior. The PVA\\/PDADMAC IPN hydrogel was synthesized using the sequential IPN method. The swelling behavior of the IPN hydrogel was studied by immersion of the gel in aqueous NaCl solutions at various concentrations and pHs. The swelling ratio decreased with an increase in NaCl
Seon Jeong Kim; Seoung Gil Yoon; Young Moo Lee; Sun I. Kim
Oxidation of polyvinyl alcohol by persulfate activated with heat, Fe 2+, and zero-valent iron
The oxidation of polyvinyl alcohol (PVA) by persulfate (S2O82?) activated with heat, Fe2+, and zero-valent iron (Fe(0)) was investigated via batch experiments. It was hypothesized that elevated temperature and the addition of Fe2+ or Fe(0) into a persulfate-water system could enhance the oxidation of PVA by activated persulfate. Increasing the temperature from 20 to 60░C or 80░C accelerated the oxidation
Seok-Young Oh; Hyeong-Woo Kim; Jun-Mo Park; Hung-Suck Park; Chohee Yoon
Immobilisation of anchorage-independent animal cells using reticulated polyvinyl formal resin biomass support particles
Immobilisation of anchorage-independent animal cells using Biomas Support Particles (BSPs) was investigated. Mouse myeloma MPC-11 cells were physically entrapped in three-dimensional reticulated polyvinyl formal (PVF) resin PSPs (3ū3ū3 mm) with matrices of relatively small pores (30¢100 Ąm) by filtering medium containing cells or incubating in a shake flask for inoculation. Physically entrapped cells became immobilised in the BSPs by forming
Hideki Yamaji; Hideki Fukuda; Yasuhiro Nojima; Colin Webb
Study of Memory Alignment of Nematic Liquid Crystals on Polyvinyl Alcohol Coatings
Polymer layers can cause memory alignment of nematic liquid crystals. We describe an experimental method to characterize this effect. We studied the temperature dependence of the memory alignment on polyvinyl alcohol coatings. We also investigated the influence of the time span during which the memory alignment is generated. We propose an adsorption-desorption mechanism by which we can explain our observations in a reasonable way.
Vetter, Peter; Ohmura, Yoshinori; Uchida, Tatsuo
Heparinized poly(vinyl alcohol)-small intestinal submucosa composite membrane for coronary covered stents
To develop a novel coating material for coronary covered stents, we prepared a kind of composite membrane which contains polyvinyl alcohol (PVA) and porcine small intestinal submucosa (SIS) powders crosslinked and heparinized by N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). The amount of immobilized heparin increased with increasing ratios of EDC:heparin, and the maximum amount was approximately 60 Ąg heparin per
Tao Jiang; Guixue Wang; Juhui Qiu; Lailong Luo; Guoquan Zhang
Electrodialytic Transport Properties of Anion-Exchange Membranes Prepared from Poly(vinyl alcohol) and Poly(vinyl alcohol-co-methacryloyl aminopropyl trimethyl ammonium chloride)
Random-type anion-exchange membranes (AEMs) have been prepared by blending poly(vinyl alcohol) (PVA) and the random copolymer-type polycation, poly(vinyl alcohol-co-methacryloyl aminopropyl trimethyl ammonium chloride) at various molar percentages of anion-exchange groups to vinyl alcohol groups, Cpc, and by cross-linking the PVA chains with glutaraldehyde (GA) solution at various GA concentrations, CGA. The characteristics of the random-type AEMs were compared with blend-type AEMs prepared in our previous study. At equal molar percentages of the anion exchange groups, the water content of the random-type AEMs was lower than that of the blend-type AEMs. The effective charge density of the random-type AEMs increased with increasing Cpc and reached a maximum value. Further, the maximum value of the effective charge density increased with increasing CGA. The maximum value of the effective charge density, 0.42 mol/dm3, was obtained for the random-type AEM with Cpc = 4.2 mol % and CGA = 0.15 vol %. A comparison of the random-type and blend-type AEMs with almost the same Cpc showed that the random-type AEMs had lower membrane resistance than the blend-type ones. The membrane resistance and dynamic transport number of the random-type AEM with Cpc = 6.0 mol % and CGA = 0.15 vol % were 4.8 ? cm2 and 0.83, respectively.
Jikihara, Atsushi; Ohashi, Reina; Kakihana, Yuriko; Higa, Mitsuru; Kobayashi, Kenichi
An increased standardised mortality ratio for liver cancer among polyvinyl chloride workers in Taiwan
Aims: To determine the standardised mortality ratio (SMR) corresponding to different causes of death in workers from polyvinyl chloride polymerisation factories in Taiwan. Methods: Retrospective cohort study of workers from six polyvinyl chloride polymerisation factories in Taiwan. A total of 3293 male workers who had been employed for at least one year during the period 1 January 1950 to 31 December 1992, and were alive on 1 January 1985 were included for analysis. Using data acquired from Taiwan's National Mortality Registry, it was found that 144 of these workers died during the period 1985¢97. The follow up rate was 99% with a total number of person-years at risk of 40 557. Results: SMR for all causes of death was 0.78, indicating a possible "healthy worker" effect. The SMR for liver cancer decreased with increasing age of first exposure to vinyl chloride monomer. This association was more prominent for workers who were first employed in the industry prior to 1970 (SMR 4.82). Medical records indicated that most liver cancers in this study were hepatocellular carcinoma. Conclusions: Polyvinyl chloride workers may experience a higher risk of developing liver cancer, particularly hepatocelluar carcinoma.
Wong, R; Chen, P; Du, C; Wang, J; Cheng, T
Acetate supplementation attenuates lipopolysaccharide-induced neuroinflammation
Glyceryl triacetate (GTA), a compound effective at increasing circulating and tissue levels of acetate was used to treat rats subjected to a continual 28 day intra-ventricular infusion of bacterial lipopolysaccharide (LPS). This model produces a neuroinflammatory injury characterized by global neuroglial activation and a decrease in choline acetyltransferase immunoreactivity in the basal forebrain. During the LPS infusion, rats were given a daily treatment of either water or GTA at a dose of 6g/kg by oral gavage. In parallel experiments free-CoA and acetyl-CoA levels were measured in microwave fixed brains and flash frozen heart, liver, kidney and muscle following a single oral dose of GTA. We found that a single oral dose of GTA significantly increased plasma acetate levels by 15 min and remained elevated for up to 4 hr. At 30 min the acetyl-CoA levels in microwave-fixed brain and flash frozen heart and liver were increased at least 2.2-fold. The concentrations of brain acetyl-CoA was significantly increased between 30 and 45 min following treatment and remained elevated for up to 4 hr. The concentration of free-CoA in brain was significantly decreased compared to controls at 240 min. Immunohistochemical and morphological analysis demonstrated that a daily treatment with GTA significantly reduced the percentage of reactive GFAP-positive astrocytes and activated CD11b-positive microglia by 40¢50% in rats subjected to LPS-induced neuroinflammation. Further, in rats subjected to neuroinflammation, GTA significantly increased the number of ChAT-positive cells by 40% in the basal forebrain compared to untreated controls. These data suggest that acetate supplementation increases intermediary short chain acetyl-CoA metabolism and that treatment is potentially anti-inflammatory and neuroprotective with regards to attenuating neuroglial activation and increasing ChAT immunoreactivity in this model.
Reisenauer, Chris J.; Bhatt, Dhaval P.; Mitteness, Dane J.; Slanczka, Evan R.; Gienger, Heidi M.; Watt, John A.; Rosenberger, Thad A.
Crystal growth of calcium carbonate on the cellulose acetate/pyrrolidon blend films in the presence of L-aspartic acid
The morphogenesis and growth process of calcium carbonate on the cellulose acetate/polyvinyl pyrrolidone (CA/PVP) blend films in the presence of L-aspartic acid was carefully investigated. The results showed that the concentration of L-aspartic acid, the initial pH value of reaction solution and temperature turned out to be important factors for the control of morphologies and polymorphs of calcium carbonate. Complex morphologies of CaCO3 particles, such as cubes, rose-like spheres, twinborn-spheres, cone-like, bouquet-like, etc. could be obtained under the different experimental conditions. The dynamic process of formation of rose-like sphere crystals was analyzed by monitoring the continuous morphological and structural evolution and components of crystals in different crystal stages. This research may provide a promising method to prepare other inorganic materials with complex morphologies.
Zhang, Xiuzhen; Xie, Anjian; Huang, Fangzhi; Shen, Yuhua
Novel degradable polymer networks containing acetal components
A novel copolymer network with acetal structure was prepared using bis[4-(vinyloxy)butyl] (4-methyl-1,3-phenylene)biscarbamate\\u000a (BECT) as the crosslinking agent. Firstly, a tri-copolymer of maleic anhydride (MAn), n-butyl vinyl ether (BVE) and 4-hydroxybutyl vinyl ether (HBVE) was synthesized via free-radical polymerization with 2,2?-azobisisobutyronitrile\\u000a as the initiator. The tri-copolymer consisted of two sorts of alternating units, MAn-alt-BVE and MAn-alt-HBVE. The linear copolymer Poly((MAn-alt-BVE)-co-(MAn-alt-HBVE)) with
XinCe Sui; Yan Shi; ZhiFeng Fu
Preliminary studies in our laboratory showed that the synthetic androgen trenbolone acetate (TA) is a good candidate for masculinizing Nile tilapia (Oreochromis niloticus) fry using short immersions. In this study we investigated the effects of TA treatment on the growth performance of Nile tilapia. We tested the potential anabolic effects of two treatments by growing treated and control fish for
Wilfrido M. Contreras-Sßnchez; Martin S. Fitzpatrick; Carl B. Schreck
In previous experiments we have found that two 3-hour immersions in trenbolone acetate (TA) can successfully masculinize Nile tilapia fry. In this study we are investigating how the concentration of TA in the immersion water changes before and after treatment to determine the amount of hormone uptake and estimate the potential for reuse of the treatment water. Nile tilapia fry
Micro-mold fabrication using cellulose acetate
Polymer materials offer numerous advantages including flexible, low cost large area displays, lightweight, easy processing, good compatibility with a variety of substrates, and easy for structural modifications. Recently electro-active polymers (EAP) have been attractive due to their potential advantages including ease of processing and control, mechanical flexibility, and economical advantage. Recently electro-active paper (EAPap) was discovered as a smart material and as an actuating material with ionic and piezoelectric effects. Before cellulose acetate (CA) micro-pattern fabrication, solvent effect of micro or nano-pore formation was investigated. Since the micropore scatter the visible light, micropores give negative effect to apply optical device. The solvent mixture of acetone/dimethylacetamide (DMAc) created large amount of micro or nanopores. The resulting films were not transparent. However, volatile single solvent (acetone) did not form pores and gave transparent film. The various shapes of photoresist, such as circle and honeycomb patterns, were fabricated onto the silicon wafer to use as the mold. Cellulose acetate (CA) was poured to the mold and peeled off from the mold. The resulting pattern exhibited uniform size of the circle or honeycomb shape without defect.
Cho, K. Y.; Lim, H. K.; Chen, Y.; Kim, Jaehwan; Kang, K. S.
Dielectric relaxation of ? -tocopherol acetate (vitamin E)
Dielectric loss spectra are reported for ? -tocopherol acetate (an isomer of vitamin E) in the supercooled and glassy states. The ? -relaxation times, ?? , measured over a 190░ range of temperatures, T , at pressures, P , up to 400MPa can be expressed as a single function of TV3.9 ( V is specific volume, measured herein as a function of T and P ). At ambient pressure, there is no dynamic crossover over eight decades of measured ?? . The relaxation spectra above the glass transition temperature Tg show ionic conductivity and an excess wing on the high-frequency flank of the ? -relaxation loss peak. Temperature-pressure superpositioning is valid for the ? process; moreover, the peak shape is constant (stretch exponent equal to 0.65). However, application of pressure changes the shape of the dielectric spectrum at higher frequencies due to the shift of the excess wing to form a resolved peak. Additionally, another relaxation process, absent at atmospheric pressure, emerges on the high-frequency side of the ? -process. We propose that this new peak reflects a more compact conformation of the ? -tocopherol acetate molecule. Drawing on the coupling model, the experimentally determined relaxation times, activation energy, and activation volume for the Johari-Goldstein process are compared to values calculated from the properties of the ? relaxation. The agreement is generally satisfactory, at least for T
Kaminski, K.; Maslanka, S.; Ziolo, J.; Paluch, M.; McGrath, K. J.; Roland, C. M.
Kaminski, K.; Maslanka, S.; Ziolo, J.; Paluch, M.; McGrath, K. J.; Roland, C. M.
Atmospheric formic and acetic acids: An overview
Interest in the role of organic acids as chemical constituents in troposphere has been growing rapidly over the past couple of decades. In addition to their presence in the atmosphere in a variety of phases, organic acids are important constituents of the global troposphere and contribute a large fraction (ś25%) to the nonmethane hydrocarbon atmospheric mixture. They contribute significantly to the acidity of precipitation and cloud water, especially in remote regions. In this review, we consider the information presently available on concentration distribution of formic and acetic acids in multiple phases and their sources in different geographical locations, i.e., midlatitude continental, tropical continental and marine sites. Photochemical reactions (i.e., ozone-olefin reaction, isoprene oxidation, gas phase reaction of formaldehyde with HO2, and aqueous phase oxidation of formaldehyde) are important sources of these acids. In midlatitude continental regions, possible sources of formic and acetic acids, in addition to photochemical reactive vehicular emission, are direct emission from vegetation and biomass burning. In tropical continental sites, direct emission from vehicles, ants, soil, vegetation, and biomass burning are the important source of these species. The probable sources at marine locations are photochemical reactions, biogenic emissions, and long-range transport from continental sites.
Khare, Puja; Kumar, N.; Kumari, K. M.; Srivastava, S. S.
Aspects of the thermal oxidation of ethylene vinyl acetate copolymer
The thermal oxidation of ethylene-vinyl acetate copolymer [EVA-17 and 28% w\\/w VA (vinyl acetate) units] has been examined by thermo-gravimetric and hydroperoxide analysis, FTIR (Fourier transform infra-red) fluorescence spectroscopy and yellowness index. Thermal analysis indicates the initial loss of acetic acid followed by oxidation and breakdown of the main chain. The degradation rate is greater in an oxygen atmosphere as
Norman S. Allen; Michele Edge; Miguel Rodriguez; Cristopher M. Liauw; Eusebio Fontan
Mesophilic syntrophic acetate oxidation during methane formation in biogas reactors
The reaction pathway for the formation of methane from acetate was investigated in sludge from 13 different biogas reactors. By following the conversion of [2-14C]acetate and [14C]bicarbonate it was shown that methane formation by syntrophic acetate oxidation was the dominating mechanism for acetotrophic methanogenesis in sludge containing high levels of salts, mainly ammonium, and volatile fatty acids. In one biogas
Anna Schn³rer; Gerhard Zellner; Bo H. Svensson
Condensation of benzaldehyde diethyl acetal with ethyl vinyl ether
Summary 1.A study was made of the condensation of benzaldehyde diethyl acetal with ethyl vinyl ether.2.It was shown that in this reaction aliphatic-aromatic ethoxy acetals of general formula C6H5 -(CHOC2H5-CH2)nCH(OC2H5)2 are formed.3.By the hydrolysis of these ethoxy acetals, aliphatic-aromatic ethoxy aldehydes were prepared.
B. M. Mikhailov; L. S. Povarov
Solution behavior and surface properties of carboxymethylcellulose acetate butyrate
Solution behavior of carboxymethylcellulose acetate butyrate (CMCAB) in acetone and ethyl acetate has been investigated by\\u000a small-angle X-ray scattering (SAXS) and capillary viscometry and correlated with the characteristics of CMCAB films. Viscosity\\u000a and SAXS measurements showed that ethyl acetate is a better solvent than acetone for CMCAB. Thin films of CMCAB were deposited\\u000a onto silicon wafers (Si\\/SiO2) by spin coating.
Jorge Amim Jr; Denise F. S. Petri; Francisco C. B. Maia; Paulo B. Miranda
Acetate metabolism and its regulation in Corynebacterium glutamicum.
The amino acid producing Corynebacterium glutamicum grows aerobically on a variety of carbohydrates and organic acids as single or combined sources of carbon and energy. Among the substrates metabolized are glucose and acetate which both can also serve as substrates for amino acid production. Based on biochemical, genetic and regulatory studies and on quantitative determination of metabolic fluxes during utilization of acetate and/or glucose, this review summarizes the present knowledge on the different steps of the fundamental pathways of acetate utilization in C. glutamicum, namely, on acetate transport, acetate activation, tricarboxylic acid (TCA) cycle, glyoxylate cycle and gluconeogenesis. It becomes evident that, although the pathways of acetate utilization follow the same theme in many bacteria, important biochemical, genetic and regulatory peculiarities exist in C. glutamicum. Recent genome wide and comparative expression analyses in C. glutamicum cells grown on glucose and on acetate substantiated previously identified transcriptional regulation of acetate activating enzymes and of glyoxylate cycle enzymes. Additionally, a variety of genes obviously also under transcriptional control in response to the presence or absence of acetate in the growth medium were uncovered. These genes, thus also belonging to the acetate stimulon of C. glutamicum, include genes coding for TCA cycle enzymes (e.g. aconitase and succinate dehydrogenase), for gluconeogenesis (phosphoenolpyruvate carboxykinase), for glycolysis (pyruvate dehydrogenase E1) and genes coding for proteins with hitherto unknown function. Although the basic mechanism of transcriptional regulation of the enzymes involved in acetate metabolism is not yet understood, some recent findings led to a better understanding of the adaptation of C. glutamicum to acetate at the molecular level. PMID:12948633
Gerstmeir, Robert; Wendisch, Volker F; Schnicke, Stephanie; Ruan, Hong; Farwick, Mike; Reinscheid, Dieter; Eikmanns, Bernhard J
Determination of Indole Acetic Acid by the Salkowsky Reaction
RECENTLY attention has been focused on the reaction of indole acetic acid with ferric ions. Cohen et al.1 have shown that indole acetic acid forms a chelate with iron at acid pH and this has been confirmed by Recaldin and Heath2. The latter state that at pH 2.6 iron slowly decomposes the indole acetic acid in the solution. The oxidation
A. M. Mayer
Microbial removal of acetate selectively from sugar mixtures
Acetic acid is an unavoidable constituent of the biomass hydrolysates generated from acetylated hemicellulose and lignin,\\u000a and acetate affects the performance of microbes used to convert these hydrolysates into biofuels or other biochemicals. In\\u000a this study, acetate was selectively removed from synthetic mixtures of glucose and xylose using metabolically engineered Escherichia\\u000a coli strains having mutations in the glucose phosphotransferase system
Arun Lakshmanaswamy; Eashwar Rajaraman; Mark A. Eiteman; Elliot Altman
Recovery of acetic acid from waste streams by extractive distillation.
Wastes have been considered to be a serious worldwide environmental problem in recent years. Because of increasing pollution, these wastes should be treated. However, industrial wastes can contain a number of valuable organic components. Recovery of these components is important economically. Using conventional distillation techniques, the separation of acetic acid and water is both impractical and uneconomical, because it often requires large number of trays and a high reflux ratio. In practice special techniques are used depending on the concentration of acetic acid. Between 30 and 70% (w/w) acetic acid contents, extractive distillation was suggested. Extractive distillation is a multicomponent-rectification method similar in purpose to azeotropic distillation. In extractive distillation, to a binary mixture which is difficult or impossible to separate by ordinary means, a third component termed an entrainer is added which alters the relative volatility of the original constituents, thus permitting the separation. In our department acetic acid is used as a solvent during the obtaining of cobalt(III) acetate from cobalt(II) acetate by an electrochemical method. After the operation, the remaining waste contains acetic acid. In thiswork, acetic acid which has been found in this waste was recovered by extractive distillation. Adiponitrile and sulfolane were used as high boiling solvents and the effects of solvent feed rate/solution feed rate ratio and type were investigated. According to the experimental results, it was seem that the recovery of acetic acid from waste streams is possible by extractive distillation. PMID:12862234
Demiral, H; Yildirim, M Ercengiz
Vapor-liquid equilibrium data for methanol, ethanol, methyl acetate, ethyl acetate, and o-xylene at 101.3 kPa
Vapor-liquid equilibrium was measured for the binary systems methanol + o-xylene, ethanol + o-xylene, methyl acetate + o-xylene and ethyl acetate + o-xylene, and for the multicomponent mixtures methanol + methyl acetate + o-xylene, ethanol + ethyl acetate + o-xylene, and methanol + ethanol + methyl acetate + ethyl acetate + o-xylene at 101.3 kPa. The Wilson and Van Laar models were compared with the UNIFAC method. Results show that the correlation was satisfactory.
Costa-Lopez, J.; Garvin, A.; Espana, F.J. [Barcelona Univ. (Spain). Chemical Engineering Dept.
Grape contribution to wine aroma: production of hexyl acetate, octyl acetate, and benzyl acetate during yeast fermentation is dependent upon precursors in the must.
Wine is a complex consumer product produced predominately by the action of yeast upon grape juice musts. Model must systems have proven ideal for studies of the effects of fermentation conditions on the production of certain wine volatiles. To identify grape-derived precursors to acetate esters, model fermentation systems were developed by spiking precursors into model must at different concentrations. Solid-phase microextraction-gas chromatgraphy mass spectrometry analysis of the fermented wines showed that a variety of grape-derived aliphatic alcohols and aldehydes are precursors to acetate esters. The C6 compounds hexan-1-ol, hexenal, (E)-2-hexen-1-ol, and (E)-2-hexenal are all precursors to hexyl acetate, and octanol and benzyl alcohol are precursors to octyl acetate and benzyl acetate, respectively. In these cases, the postfermentation concentration of an acetate ester increased proportionally with the prefermentation concentration of the respective precursor in the model must. Determining viticultural or winemaking methods to alter the prefermentation concentration of precursor compounds or change the precursor-to-acetate ester ratio will have implications upon the final flavor and aroma of wines. PMID:22332880
Dennis, Eric G; Keyzers, Robert A; Kalua, Curtis M; Maffei, Suzanne M; Nicholson, Emily L; Boss, Paul K
Polyvinyl alcohol-polyvinyl pyrrolidone thin films provide local short-term release of anti-inflammatory agents post spinal cord injury.
Spinal cord injury (SCI) triggers a large inflammatory response that results in exacerbated tissue damage. Locally delivering anti-inflammatory drugs could mitigate this secondary wave of degeneration. The mitogen-activated protein kinase family members p38 and c-Jun N-terminal kinase (JNK) play important roles in the inflammatory response and cell death. We propose that the use of polymer thin films, made of polyvinyl alcohol and polyvinyl pyrrolidone blends (PVA-PVP), can be used to provide local release of inhibitors to p38 and JNK post-SCI. Release studies performed in vitro confirmed the inhibitors could be released from the film for up to 7 days. The thin film was also tested for its surgical feasibility using a cervical contusion model of SCI in adult female rats. Films with or without the inhibitors were placed subdurally over the injury site immediately following SCI. Animals were sacrificed 5 days post-SCI and spinal cord tissue above and below the injury site was harvested. Additionally, films were removed for analysis. Scanning electron microscopy confirmed the anti-fouling properties of the PVA-PVP film. Tissue histology confirmed that the films themselves did not generate a large immune response, but they did compress the tissue slightly at its placement above the injury site. Finally, quantitative Western blot analysis determined the films loaded with p38 and JNK inhibitors delivered bioactive agents to the injury site and resulted in a significantly decreased amount of pro-cell death proteins. These data indicate that PVA-PVP films can be used to effectively deliver drugs to a SCI site. PMID:22821814
Comolli, Noelle; Donaldson, Olivia; Grantier, Nathan; Zhukareva, Victoria; Tom, Veronica J
Supercritical water oxidation of polyvinyl alcohol and desizing wastewater: influence of NaOH on the organic decomposition.
Polyvinyl alcohol is a refractory compound widely used in industry. Here we report supercritical water oxidation of polyvinyl alcohol solution and desizing wastewater with and without sodium hydroxide addition. However, it is difficult to implement complete degradation of organics even though polyvinyl alcohol can readily crack under supercritical water treatment. Sodium hydroxide had a significant catalytic effect during the supercritical water oxidation of polyvinyl alcohol. It appears that the OH- ion participated in the C-C bond cleavage of polyvinyl alcohol molecules, the CO2-capture reaction and the neutralization of intermediate organic acids, promoting the overall reactions moving in the forward direction. Acetaldehyde was a typical intermediate product during reaction. For supercritical water oxidation of desizing wastewater, a high destruction rate (98.25%) based on total organic carbon was achieved. In addition, cases where initial wastewater was alkaline were favorable for supercritical water oxidation treatment, but salt precipitation and blockage issues arising during the process need to be taken into account seriously. PMID:24520696
Zhang, Jie; Wang, Shuzhong; Guo, Yang; Xu, Donghai; Gong, Yanmeng; Tang, Xingying
Polypyrrole based strong acid catalyst for acetalization
Novel polypyrrole based acid catalyst has been synthesized through the neutralization reaction of polypyrrole and sulfuric acid. The polypyrrole based acid owned the acidity as high as 6.0 mmol/g, which was much higher than that of the traditional solid acids such as Nafion and Amberlyst-15 (0.8 mmol/g). The catalytic activities of the novel solid acid were investigated through the acetalization. The results showed that the novel solid acid held high activities for the reactions. Furthermore, the recycled activities of the catalyst indicated that the solid acid owned high stability during the catalytic process and little acid sites dropped from polypyrrole. The high acidity and stability made the novel polypyrrole based acid hold great potential for the green chemical processes.
Liang, Xuezheng; Cheng, Yuxiao; Qi, Chenze
Dihydro-myricetin hexa-acetate.
In the title compound, C(27)H(24)O(14), also known as 2,3-di-acetoxy-5-[(2RS,3RS)-3,5,7-triacetoxy-4-oxochromen-2-yl]phenyl acetate, the heterocyclic ring adopts a distorted half-chair conformation, with two C atoms displaced by 0.1775?(16) and -0.5950?(16)?┼ from the mean plane of the other four atoms. The dihedral angle between the aromatic rings is 57.81?(8)░. In the crystal, the mol-ecules inter-act by C-H?O bonds, aromatic ?-? stacking [centroid-centroid separation = 3.6206?(9)?┼] and C-H?? inter-actions. PMID:21587600
Li, Wei; Bhadbhade, Mohan; Hook, James; Zhao, Jian
Synthesis and regeneration of lead (IV) acetate
Lead acetate [Pb(O{sub 2}CMe){sub 4}] was easily synthesized from a warm solution of Pb{sub 3}O{sub 4}, HO{sub 2}CMe and O(OCMe){sub 2} following literature preparations when the appropriate measures to minimize water contamination were followed. Furthermore, Pb(O{sub 2}CMe){sub 4} which has been decomposed (evidenced by the appearance of a purple color due to oxidation) can be regenerated using a similar preparatory route. Introduction of Pb(O{sub 2}CMe){sub 4} from the two routes outlined above into the IMO process for production of PZT thin films gave films with comparable ferroelectric properties to commercially available Pb(O{sub 2}CMe){sub 4} precursors. However, the freshly synthesized material yields PZT films with better properties compared to the recycled material.
Boyle, T.J.; Al-Shareef, H.N.; Moore, G.J. [Sandia National Labs., Albuquerque, NM (United States). Advanced Materials Lab.
Indole-3-acetic Acid in Douglas Fir
We sought evidence for the occurrence and seasonal variation of indole-3-acetic acid (IAA) in shoots of Douglas fir (Pseudotsuga menziesii [Mirb.] Franco). Collections obtained in December and June were extracted with methanol and diethyl ether. Extracts were purified by solvent partitioning and with Sephadex LH-20. Qualitative and quantitative information was acquired by gas-liquid chromatography of methyl, trimethylsilyl, or both derivatives of plant extract components. Analysis was performed with polar (XE-60) and moderately polar (Hi-Eff-8-BP) stationary phases. Results from three collections demonstrated that IAA does occur in Douglas fir and that amounts vary seasonally. Mass analysis of the proposed endogenous IAA peak from two representative extracts supported gas-liquid chromatography data and established the presence of IAA in Douglas fir.
Deyoe, David R.; Zaerr, Joe B.
Potassium acetate adds flexibility to drilling muds
Potassium acetate (KC/sub 2/H/sub 3/O/sub 2/, or simply KAC), since 1986, has proven effective as a drilling fluid additive in over 30 wells both onshore and offshore South Texas. KAC has given potassium-base drilling fluids more flexibility, improved efficiency, and offered an environmentally acceptable alternative to potassium chloride (KCl) muds. The use of soluble potassium in drilling fluids has been successful in controlling troublesome shales. The potassium ion has a stabilizing effect that inhibits the swelling and dispersion of water-sensitive shale formations. KAC is completely soluble in fresh or saltwater and provides 40%, by weight, potassium. This compares favorably with other potassium-containing materials.
Gillenwater, K.E.; Ray, C.R.
Chemistry of acetals. Communication 19. Structure of acetals and their reactivity in reaction with ethyl vinyl ether
Summary 1.From a comparison of data from our own work and from the literature on the yields of the primary products of chain-growth reactions of mono- and di-acetals of various structures it is shown that in the case of saturated acetals the cause of the different reactivities of the acetals lies mainly in the presence or absence of electronaccepting substituents
L. A. Yanovskaya
Toughening of poly(lactic acid) by ethylene- co-vinyl acetate copolymer with different vinyl acetate contents
The well-known bio-based and biocompostable poly(lactic acid), PLA, suffers from brittleness and a low heat distortion temperature. In this paper, we address a possible route to make PLA tough(er) by blending with ethylene-co-vinyl acetate (EVA) with different vinyl acetate contents. The compatibility and phase morphology of the PLA\\/EVA blends was controlled by the ratio of vinyl acetate and ethylene in
P. Ma; D. G. Hristova-Bogaerds; J. G. P. Goossens; Y. Zhang; P. J. Lemstra
Formulation and evaluation of an in situ gel forming system for controlled delivery of triptorelin acetate.
The novel physical hydrogels composed of chitosan or its water soluble derivatives such as carboxymethyl chitosan (CMCh) and sodium carboxymethyl chitosan (NaCMCh) and opened ring polyvinyl pyrrolidone (OP-PVP) were used as a controlled delivery system for triptorelin acetate, a luteinizing-releasing hormone agonist. The in situ gel forming system designed according to physical interactions such as chains entanglements and hydrophilic attractions especially h-bonds of chitosan and/or NaCMCh and OR-PVP. In order to increase in situ gel forming rate the chitosan microspheres prepared through spray drying technique. The chitosan or NaCMCh/OR-PVP blends prepared at different ratios (0.05, 0.10, 0.12, 0.16, 0.20 and 0.24) and suspended in sesame oil as non-aqueous vehicle at different solid content (10-30%). The suitable ratio of polymers with faster in situ gel forming rate was selected for in vivo studies. The gel formation and drug release from the system was evaluated both in vitro and in vivo. In vitro and in vivo results were compared with Diphereline SR 3.75mg, a commercially available controlled delivery system of triptorelin. In vitro release studies showed a sustained release profile for about 192h with first order kinetics. In vivo studies on male rats by determination of serum testosterone were confirmed the acceptable performance of in situ gel forming system compared with Diphereline SR in decreasing the serum testosterone level for 35days, demonstrating the potential of the novel in situ gel forming system for controlled delivery of peptides. PMID:21946260
Abashzadeh, Sh; Dinarvand, R; Sharifzadeh, M; Hassanzadeh, G; Amini, M; Atyabi, F
Oxidation of indole-3-acetic acid to oxindole-3-acetic acid by an enzyme preparation from Zea mays
Indole-3-acetic acid is oxidized to oxindole-3-acetic acid by Zea mays tissue extracts. Shoot, root, and endosperm tissues have enzyme activities of 1 to 10 picomoles per hour per milligram protein. The enzyme is heat labile, is soluble, and requires oxygen for activity. Cofactors of mixed function oxygenase, peroxidase, and intermolecular dioxygenase are not stimulatory to enzymic activity. A heat-stable, detergent-extractable component from corn enhances enzyme activity 6- to 10-fold. This is the first demonstration of the in vitro enzymic oxidation of indole-3-acetic acid to oxindole-3-acetic acid in higher plants.
Reinecke, D. M.; Bandurski, R. S.
Oxidation of Indole-3-Acetic Acid to Oxindole-3-Acetic Acid by an Enzyme Preparation from Zea mays1
Reinecke, Dennis M.; Bandurski, Robert S.
Contribution of acetate to butyrate formation by human faecal bacteria.
Acetate is normally regarded as an endproduct of anaerobic fermentation, but butyrate-producing bacteria found in the human colon can be net utilisers of acetate. The butyrate formed provides a fuel for epithelial cells of the large intestine and influences colonic health. [1-(13)C]Acetate was used to investigate the contribution of exogenous acetate to butyrate formation. Faecalibacterium prausnitzii and Roseburia spp. grown in the presence of 60 mm-acetate and 10 mm-glucose derived 85-90 % butyrate-C from external acetate. This was due to rapid interchange between extracellular acetate and intracellular acetyl-CoA, plus net acetate uptake. In contrast, a Coprococcus-related strain that is a net acetate producer derived only 28 % butyrate-C from external acetate. Different carbohydrate-derived energy sources affected butyrate formation by mixed human faecal bacteria growing in continuous or batch cultures. The ranking order of butyrate production rates was amylopectin > oat xylan > shredded wheat > inulin > pectin (continuous cultures), and inulin > amylopectin > oat xylan > shredded wheat > pectin (batch cultures). The contribution of external acetate to butyrate formation in these experiments ranged from 56 (pectin) to 90 % (xylan) in continuous cultures, and from 72 to 91 % in the batch cultures. This is consistent with a major role for bacteria related to F. prausnitzii and Roseburia spp. in butyrate formation from a range of substrates that are fermented in the large intestine. Variations in the dominant metabolic type of butyrate producer between individuals or with variations in diet are not ruled out, however, and could influence butyrate supply in the large intestine. PMID:15182395
Duncan, Sylvia H; Holtrop, Grietje; Lobley, Gerald E; Calder, A Graham; Stewart, Colin S; Flint, Harry J
Heterogeneous catalyst for the production of acetic anhydride from methyl acetate
This invention relates to a process for producing acetic anhydride by the reaction of methyl acetate, carbon monoxide, and hydrogen at elevated temperatures and pressures in the presence of an alkyl halide and a heterogeneous, bifunctional catalyst that contains an insoluble polymer having pendant quaternized phosphine groups, some of which phosphine groups are ionically bonded to anionic Group VIII metal complexes, the remainder of the phosphine groups being bonded to iodide. In contrast to prior art processes, no accelerator (promoter) is necessary to achieve the catalytic reaction and the products are easily separated from the catalyst by filtration. The catalyst can be recycled for consecutive runs without loss in activity. Bifunctional catalysts for use in carbonylating dimethyl ether are also provided.
Ramprasad, D.; Waller, F.J.
Ramprasad, Dorai (Allentown, PA); Waller, Francis Joseph (Allentown, PA)
Ionic conduction of novel polymer composite films based on partially phosphorylated poly(vinyl alcohol)
New ion-conducting polymer composite films have been prepared, and their ionic conducting properties have been investigated. The polymer composite films are fabricated from partially phosphorylated poly(vinyl alcohol) with tetramethylammonium salt (P-PVAĘMe4N+) and poly(acrylic acid) (PAA) or poly(ethylene glycol) (PEG). For P-PVAĘMe4N+\\/PEG composite films, the ionic conductivity and carrier density sharply increased, and carrier mobility sharply decreased around [PEG]\\/[PO3]P-PVA of 2.
Naomi Takada; Toshiki Koyama; Masahiro Suzuki; Mutsumi Kimura; Kenji Hanabusa; Hirofusa Shirai; Seizo Miyata
Poly(vinyl chloride)-based macrocyclic membrane sensors for magnesium
Poly(vinyl chloride)-based membranes of macrocycles 4,11-dimethyl-2,4,9,11-tetraethyl-1,5,8,12-tetraaza cyclotetradeca-1,8-diene (I) and 4,11-dioxa-2,9-dimethyl-1,5,8,12-tetraaza cyclotetradeca-1,8-diene (II) with sodium tetraphenyl borate (STB) as an anion excluder and dibutyl phthalate (DBP), dioctyl phthalate (DOP), dibutylbutyl phosphonate (DBBP) and 1-chloronaphthalene (CN) as plasticizing solvent mediators were prepared and investigated as magnesium selective electrodes. The best performance was observed having the composition (II)¢PVC¢STB¢DBP in the ratio 2:10:1:7, which
Seema Baniwal; S. Chandra; A. Panwar; A. K. Singh
Aluminum(III) selective potentiometric sensor based on morin in poly(vinyl chloride) matrix
Al3+ selective sensor has been fabricated from poly(vinyl chloride) (PVC) matrix membranes containing neutral carrier morin as ionophore. Best performance was exhibited by the membrane having composition as morin:PVC:sodium tetraphenyl borate:tri-n-butylphosphate in the ratio 5:150:5:150 (w\\/w, mg). This membrane worked well over a wide activity range of 5.0ū10?7 to 1.0ū10?1M of Al3+ with a Nernstian slope of 19.7▒0.1mV\\/decade of Al3+
Vinod K. Gupta; Ajay K. Jain; Gaurav Maheshwari
Monitoring of Temperature Fatigue Failure Mechanism for Polyvinyl Alcohol Fiber Concrete Using Acoustic Emission Sensors
The applicability of acoustic emission (AE) techniques to monitor the mechanism of evolution of polyvinyl alcohol (PVA) fiber concrete damage under temperature fatigue loading is investigated. Using the temperature fatigue test, real-time AE monitoring data of PVA fiber concrete is achieved. Based on the AE signal characteristics of the whole test process and comparison of AE signals of PVA fiber concretes with different fiber contents, the damage evolution process of PVA fiber concrete is analyzed. Finally, a qualitative evaluation of the damage degree is obtained using the kurtosis index and b-value of AE characteristic parameters. The results obtained using both methods are discussed.
Li, Dongsheng; Cao, Hai
Superselective arterial embolisation with a liquid polyvinyl alcohol copolymer in patients with acute gastrointestinal haemorrhage
ObjectivesĀĀTo evaluate the results of emergency embolisation in acute arterial bleeding of the gastrointestinal tract with a liquid polyvinyl\\u000a alcohol copolymer from two centres.\\u000a \\u000a \\u000a \\u000a \\u000a MethodsĀĀWe retrospectively analysed 16 cases (15 patients) of acute arterial bleeding of the gastrointestinal tract where emergency\\u000a embolotherapy was performed by using the copolymer when acute haemorrhage was not treatable with endoscopic techniques alone.\\u000a Cause of
Markus Lenhart; Christian Paetzel; Michael Sackmann; Hans Schneider; Ernst Michael Jung; Andreas G. Schreyer; Stefan Feuerbach; Niels Zorger