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Our peer-reviewed sister journal: Lignocellulose (no author payment)
Past conference: NWBC 2015
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BioResources, Volume 7, Issue 2
May 2012
NOTE: Each current issue of BioResources continues to build as new articles are approved.
Lucia, L. A. (2012). "Biomass education in the twenty-first century," BioRes. 7(2), 1383-1384.
The importance of teaching, for the development of economies, cultures, and the enrichment of people's lives cannot be overstated. These days biomass and bioenergy teaching has a pivotal role to play in influencing all of the aforementioned areas of life, since fossil fuels are becoming depleted. However, what good is teaching if it cannot be communicated in an intelligible, persuading, and egalitarian manner? A dynamic educational construct between "teacher" and "student" will be the chief mode of promoting knowledge and provoking research for engendering more knowledge. This editorial attempts to show how teaching is a living and symbiotic discipline that we typically take for granted, but once we do it right, we have the power to change the world as we know it. We will briefly explore the example of BioSUCCEED, a platform at NC State University, as a means of communicating knowledge related to biomass and bioenergy. PDF
Shen, J., and Qian, X. (2012). "Application of fillers in cellulosic paper by surface filling: An interesting alternative or supplement to wet-end addition," BioRes. 7(2), 1385-1388.
The application of fillers at the surface of cellulosic paper is an interesting and industrially-commercialized but not very well-known concept, in which the filler particles are essentially added to the voids of the fibrous matrixes. This so-called "surface filling" can be achieved by the use of fillers together with a polymer solution via film press or size press, an approach that is distinct from both wet-end filling and conventional coating of paper. As an easily practicable process, surface filling has some advantages over direct wet-end addition of fillers, such as minimizing the adverse effects of filler addition on paper strength. Efficient surface filling is somewhat dependent on the specific characteristics of both fillers and fibrous matrixes. Surface filling may provide interesting possibilities for the papermaking discipline; for example, it would open the door to maximizing the cost-effectiveness of paper mills, and efficiently adding new functionalities to cellulosic paper. From both practical and fundamental points of view, systematic exploration and understanding of surface filling of cellulosic paper would be of great significance to the papermaking industry. PDF
López Leal, M. A., Cortés Martínez, R., Alfaro Cuevas Villanueva, R., Martínez Flores, H. E., and Cortés Penagos, C. d. J. (2012). "Arsenate biosorption by iron-modified pine sawdust in batch systems: Kinetics and equilibrium studies," BioRes. 7(2), 1389-1404.
The biosorption of As(V) from aqueous solutions by pine sawdust chemically modified with iron in batch systems was investigated. The loading process of Fe in this biomaterial was achieved by hydrolysis of two different ferric salts. This modification of sawdust is an attempt to improve As(V) biosorption for practical applications. The kinetics and maximum biosorption capacities of the unmodified and modified pine sawdust were evaluated. It was found that the pseudo-second order model described the As(V) biosorption kinetic data and the Langmuir-Freundlich equation described the arsenate sorption equilibrium. These results indicated that the sorption mechanism was chemisorption on a heterogeneous material. The pH effects governing biosorption capacities were also evaluated, showing a decrease as pH value rises, indicating that this biosorption process is highly pH-dependent. The estimated maximum biosorption capacities of As(V), based on the Langmuir-Freundlich fit to the data were, at pH 4, 4.4 mg/g of untreated sawdust, (UN-SW), 12.85 mg/g of ferric chloride modified sawdust (FeCl-SW), and 6 mg/g of ferric nitrate modified sawdust (FeNit-SW); and at pH 7, 2.6 mg/g of UN-SW, 5.9 mg/g of FeCl-SW, and 4.6 mg/g of FeNit-SW. Sorption capacities of iron-modified pine sawdust were evidently higher than other similar biosorbents previously reported. PDF
Lv, Z., Dong, J., and Zhang, B. (2012). "Rapid identification and detection of flavonoid compounds from bamboo leaves by LC-(ESI)-IT-TOF/MS," BioRes. 7(2), 1405-1418.
This paper provides an applicable approach to identifying flavonoid compounds from bamboo leaves extracts, based on the use of the powerful Liquid Chromatography Electrospray Ionization source in combination with hybrid Ion Trap and high-resolution Time-of-flight Mass Spectrometry (LC-(ESI)-IT-TOF/MS). The strategy involves four procedural steps including searching flavonoid components based on an ultraviolet spectrum scan, getting the accurate mass of flavonoid components parent ion, retrieving the corresponding formula by software, and speculating as to the chemical structure according to mass spectrum decomposition rules. The presently developed methodology has been well proven to be useful and valuable by successful application to the identification of flavonoid components from Dendrocalamopsis oldham leaves. All of the 13 flavonoid components detected have been successfully identified by this approach, except that it failed to confirm 3 flavonoid component chemical structures. The calibration curves of two flavonoid components (orientin and vitexin) that had been identified in bamboo leaves showed a good linear fit (R2≥0.9998) in the concentration range of 6.25 to 200 mg/L. The limits of detection (LOD) were less 0.02 mg/L (S/N=3), and the estimated limits of quantification (LOQ) were less 0.06 mg/L (S/N=10). Intra- and inter-day relative standard deviations were less than 1.04 and 1.82%, respectively. PDF
Terzi, E., Dogu, D., Kurt, F., Kartal, S. N., and Green III, F. (2012). "Effects of leaching medium on leachability of wood preserving N'N-hydroxynapthalimide (NHA)," BioRes. 7(2), 1419-1430.
Laboratory leaching test procedures usually call for the use of distilled or deionized water; however, treated wood is generally exposed to different types of water, soil, and weather conditions. Thus, factors such as salinity, hardness, pH, temperature etc. might be important in the release of different amounts of biocide compounds. This study evaluates the release of the sodium salt of the calcium precipitating and wood preserving agent N'N-hydroxynapthalimide (NHA) from treated wood specimens exposed to different types of leaching media. Scots pine wood specimens were treated with NHA at three different solution strengths. Treated specimens were then leached with distilled water, tap water, rain water, synthetic sea water, natural sparkling water, or 1% CaCO3 solutions for 2 weeks. Leaching with higher ion concentrations reduced NHA losses from the specimens in comparison with that of distilled water and rain water leaching trials. Microscopic evaluations were in good accordance with the results from leaching trials, revealing NHA precipitation onto the tori of pit elements and tracheids. In distilled water and rain water leaching trials, less NHA precipitation on to the tori of pit membranes and tracheid surfaces was observed, whilst the specimens leached with tap water, 1% CaCO3, sea water, and sparkling water showed higher NHA precipitations on the cell elements. We conclude that the leaching of NHA from treated wood can be decreased by precipitation with ions coming from tap water, sea water, sparkling water, and 1% CaCO3 solutions as leaching media rather than distilled water or rain water with no or much less ion composition. PDF
Grünewald, T., Ostrowski, S., Petutschnigg, A., Musso, M., and Wieland, S. (2012). "Structural analysis of wood-leather panels by Raman spectroscopy," BioRes. 7(2), 1431-1439.
Besides other ligno-cellulosic materials such as straw, rice husks, or bagasse, wet blue particles from leather production are a promising new raw material stock for wood-based panels, as they offer not only a high availability, but increase the properties of the panel with regard to fire resistance or mechanical characteristics. A panel with a mixture of 42.5% wood fibers, 42.5% wet blue leather particles, and 15% lignin adhesive was produced, and an inhomogeneous sample was prepared. An area of 9 x 10 mm was rasterized and scanned by means of Raman Spectroscopy. Furthermore, the reference spectra of the constituents, i.e. wood fiber, wet blue leather particle, and lignin powder were recorded. The obtained data were treated and analyzed using chemometric methods (principal components analysis PCA and cluster analysis). An important finding was that the reference data were not directly represented in the panels' spectra, and the correlation matrix of the PCA was not applicable to the panel data. This indicated that chemical changes might take place during the pressing. After processing the panel Raman spectra with the help of PCA and cluster analysis, three distinctive clusters were obtained, discriminating wood, leather, and mixed regions. With the assigned spectral information, it was possible to create a spectral image of the surface. PDF
Mamiński, M. Ł., Szymański, R., Parzuchowski, P., Antczak, A., and Szymona, K. (2012). "Hyperbranched polyglycerols with bisphenol A core as glycerol-derived components of polyurethane wood adhesives," BioRes. 7(2), 1440-1451.
Two hyperbranched polyglycerols (HBPGs) and one oligoglycerol containing bisphenol A in the core of the molecule were synthesized from glycerol carbonate and applied as polyols in 2-component polyurethane adhesive systems. It was shown that mechanical performance of the joints made in solid wood depended on the hydroxyl functionality of the polyglycerol as well as on the type of the isocyanate used as a cross-linker. The shear strengths of the best-performing joints exceeded that of the substrate. Eventually, it was proved that hyperbranched polyglycerols might be convenient glycerol-derived raw materials for polyurethane adhesives. PDF
Dungani, R., Bhat, I. u. H., Abdul Khalil, H. P. S., Naif, A., and Hermawan, D. (2012). "Evaluation of antitermitic activity of different extracts obtained from Indonesian teakwood (Tectona grandis L.f)," BioRes. 7(2), 1452-1461.
The antitermitic activityof different extracts obtained from Tectona grandis L.f was investigated against Coptotermes curvignathus (Holmgren). The main objective of this work was to determine the mortality rate of termites by the teak wood extracts. Different extracts exhibited different degree of antitermitic activity. A teak wood with age of 39-59 years and 59-79 years were selected from Purwakata and Cepu regions of Indonesia, respectively. As per earlier reports, quinones are considered as toxic to termites, and these quinones are found in abundance in teak wood. Among the extracts of petroleum ether, acetone/water (9:1), and ethanol/water (8:2), the acetone/water (9:1) extracts exhibited strong activity. The surface morphology of extracted wood samples was observed by scanning electron microscopy in order to reveal evidence of change. PDF
Chen, Q., Ni, Y., and He, Z. (2012). "Substitution of high-yield-pulp for hardwood bleached kraft pulp in paper production and its effect on alkenyl succinic anhydride sizing," BioRes. 7(2), 1462-1473.
In recent years there has been an increasing interest in using high-yield pulp (HYP) as a partial replacement for hardwood bleached kraft pulp (HWBKP) in the production of high-quality fine papers as a cost-effective way of improving the product performance. This study investigated the substitution of HYP for HWBKP and its effect on the Alkenyl Succinic Anhydride (ASA) sizing performance. The results showed that the substitution of an aspen HYP for HWBKP can increase the ASA sizing performance at a HYP substitution as high as 15 to 20%. The ASA addition sequence has an influence on the ASA sizing performance and first adding ASA to the HYP followed by mixing with kraft pulps was the preferred method. Using precipitated calcium carbonate (PCC) as a paper filler at a dosage of less than 20% can increase the ASA sizing performance due to the contribution of the calcium soap of the hydrolysed ASA. A PCC dosage greater than 20% resulted in a negative impact on the sizing performance. It was also found that different PCC loading sequences can also affect the ASA sizing performance. PDF
Chen, Y., Fan, Y., Tshabalala, M. A., Stark, N. M., Gao, J., and Liu, R. (2012). "Optical property analysis of thermally and photolytically aged Eucalyptus camaldulensis chemithermomechanical pulp (CTMP)," BioRes. 7(2), 1474-1487.
To investigate the optical properties of chemithermomechanical pulp (CTMP) from Eucalyptus camaldulensis , one group of samples of CTMP was aged by heating, and another group was first subjected to bleaching with different bleaching agents, and then aging by exposure to sunlight. Chromophores were analyzed using diffuse reflectance UV-Vis spectra (DRUV), and the brightness and color parameters (L*, a*, b*) were analyzed using colorimetry. Results showed that the color reactions of the pulp, upon heating, were enhanced in the presence of moisture. There was a linear relationship between the pulp initial moisture content (MC) and the intensity of UV-Vis absorption. The contribution of different chromophores to pulp color was analyzed with the help of bleaching agents: hydrogen peroxide, sodium dithionite, and sodium borohydride. Sodium borohydride and hydrogen peroxide treatments resulted in a decrease in the absorption band at 280 nm along with the shoulder near 320 nm, which could be attributed to conjugated C=O and C=C systems. Similarly, sodium dithionite treatment also led to a decrease in absorption of the carbonyls and double bonds conjugated with aromatic double bonds. The chromaticity parameters of bleached pulp increased after exposure to sunlight. A correspondingly higher concentration of quinoid structures was found. PDF
Martín-Sampedro, R., Rodríguez, A., Requejo, A., and Eugenio, M. E. (2012). "Improvement of TCF bleaching of olive tree pruning residue pulp by addition of a laccase and/or xylanase pre-treatment," BioRes. 7(2), 1488-1503.
This study aimed at assessing the biobleachability of soda pulps obtained from olive tree pruning residue. The enzymatic (LMS) pre-treatment was applied prior to a simple totally chlorine free (TCF) bleaching sequence, consisting of an alkaline extraction and a hydrogen peroxide stage. Additionally, the effect of adding xylanase jointly with or prior to LMS was evaluated. All of these enzymatic pre-treatments were associated with an enhancement of the bleaching sequence. The best results were found when both enzymes were applied in the same stage: lowest hydrogen peroxide consumption (63 percent); kappa number, 11.6; brightness, 46 percent ISO. The mechanical properties observed were similar to those reported by other authors who have studied pulps from olive tree pruning residue. Finally, bleached pulps were subjected to accelerated ageing in order to assess the evolution of brightness and colorimetric properties. Although biobleached pulps showed lower stability upon ageing, the best optical properties, even after ageing, were observed in pulps treated with both xylanase and laccase. PDF
Neto, V. d. O. S., Carvalho, T. V., Honorato, S. B., Gomes, C. L., Barros, F. C. F., Araújo-Silva, M. A., Freire, P. T. C., and Nascimento, R. F. (2012). "Coconut bagasse treated by thiourea/ammonia solution for cadmium removal: Kinetics and adsorption equilibrium," BioRes. 7(2), 1504-1524.
Coconut bagasse, an agricultural solid waste was used as biosorbent for the removal of cadmium after modification with thiourea. The adsorption of Cd2+ was studied at pH 5.5. Langmuir, Freundlich, and Temkin isotherms were used to model the adsorption equilibrium data, and it was found that the system followed the Langmuir and Temkin isotherms. The adsorption capacity of the biosorbent was found to be 35.97 mg g-1, which is higher or comparable to the adsorption capacity of various adsorbents reported in literature. Kinetic studies showed that the adsorption followed a pseudo-second-order rate model. PDF
Bustos Avila, C., Gacitúa Escobar, W., Cloutier, A., Fang, C.-H., and Valenzuela Carrasco, P. (2012). "Densification of wood veneers combined with oil-heat treatment. Part III: Cell wall mechanical properties determined by nanoindentation," BioRes. 7(2), 1525-1532.
Compression under the effect of heat and steam, also called thermo-hygromechanical (THM) densification, can increase wood density and therefore improve its strength, stiffness, and hardness. Oil-heat treatment (OHT) is also known to reduce wood's hygroscopicity and improve dimensional stability. A combination of both treatments can therefore produce wood with improved mechanical properties and dimensional stability. The objective of this project was to determine cell wall mechanical properties of THM-densified and OHT wood. Trembling aspen veneers were densified by a THM process and subsequently treated in canola oil at 200 and 220°C. Nanoindentations were performed in earlywood cell walls. The results show that cell wall longitudinal modulus of elasticity increased significantly from 13.5 GPa for the control to a maximum of 18.2 GPa for THM densified wood with or without OHT. Cell wall hardness increased from 0.27 GPa to a maximum of 0.43 GPa. Both THM densification and OHT significantly increased cell wall hardness. Therefore, the increase in mechanical properties of THM-densified and OHT wood can be due to an increase in wood density resulting from a reduction in porosity but also to an increase in the mechanical properties of the cell wall. PDF
Banerjee, S., Le, T., Haynes, R. D., and Bradbury, J. E. (2012). "Solubilizing and detackifying stickies with beta-cyclodextrin," BioRes. 7(2), 1533-1539.
ß-Cyclodextrin (ß-CD) solubilizes stickies from deinked pulp, commercial adhesive formulations, or magazine inserts, which demonstrates its potential as a washing aid. A new test to simulate coater scratches is described; it involves scraping the test paper sample across the surface of a thin layer chromatography plate and measuring the degree of scratching on the plate. Scratching was significantly reduced when the paper was pre-treated with ß-CD. A trial at a recycle paper mill confirmed that ß-CD reduces the tack of filtrate components. PDF
Ding, T. Y., Hii, S. L., and Ong, L. G. A. (2012). "Comparison of pretreatment strategies for conversion of coconut husk fiber to fermentable sugars," BioRes. 7(2), 1540-1547.
In the present study, coconut husk was employed as biomass feedstock for production of bioethanol, due to its abundance in Malaysia. Due to the complex structures of coconut husk, a pretreatment process is crucial in extracting fermentable sugars from the embedded cellulose matrix for subsequent ethanol fermentation process. The ground coconut husk was subjected to three different pretreatment processes inclusive of thermal, chemical, and microwave-assisted-alkaline techniques, prior to enzymatic hydrolysis and fermentation process. The composition profile of coconut husk was significantly altered upon the microwave-assisted-alkaline treatment as compared to the untreated sample, with the cellulose content increasing from 18-21% to 38-39% while lignin content decreased from 46-53% to 31-33%. Among the pretreatment methods applied, enzymatic hydrolysis of coconut husk pretreated by microwave-assisted-alkaline method recorded the highest yield of fermentable sugars, 0.279 g sugar/g substrate. SEM imaging showed the obvious and significant disruption of coconut husks' structure after microwave-assisted-alkaline pretreatment. In conclusion, by employing suitable pretreatment technique in treating the lignocellulosic materials of coconut husk, the extracted fermentable sugar is a potential substrate for bioethanol production. PDF
Liu, Z., Jiang, Z., Cai, Z., Fei, B., Yu, Y., and Liu, X. (2012). "Dynamic mechanical thermal analysis of moso bamboo (Phyllostachys heterocycla) at different moisture content," BioRes. 7(2), 1548-1557.
Bamboo is a type of biomass materials that has great potential as a bio-energy resource in China. The thermal-mechanical behavior of bamboo plays an important role in the formation process of pellets. To investigate the effect of moisture content (MC) on thermal-mechanical behavior of bamboo, the storage modulus and loss factor of moso bamboo was determined using dynamic mechanical thermal analysis (DMTA) from -50 to 150 oC. The experimental results showed that the general feature of bamboo thermal-mechanical properties with temperature is similar to other cellulosic materials, and they are affected by MC. A substantial decrease of storage modulus over the entire temperature range implies that bamboo underwent a glass to rubber transition. Bamboo, at lower MC, has a higher storage modulus, which decreases the mechanical strength of pellets. The loss factor exhibited two major transitions for all samples. There was an α-transition (α1), attributed to glass transition of lignin, peaking in a higher temperature range. The second major relaxation (α2), located in a lower temperature range, was attributed to glass transition of hemicelluloses. Activating lignin and hemicelluloses using moisture and temperature in the temperature range of glass transition can be very helpful to achieve durable particle-particle bonding. PDF
El Moussaouiti, M., Barcha, B., Alves, E. F., and Francis, R. C. (2012). "Kraft pulping characteristics of three Moroccan eucalypti. Part 1. Physical and chemical properties of woods and pulps," BioRes. 7(2), 1558-1568.
Two eucalyptus hybrids (EGC 39, EGC 241), resulting from crosses between Eucalyptus grandis and Eucalyptus camaldulensis, were investigated to see if they could produce kraft papermaking fibers with low lignin and adequate physical properties. The two hybrids were harvested at an age of 8 years along with 6-8 year old Eucalyptus camaldulensis (Rostrata). All three eucalypti were grown in the area of Gharb in the North-West of Morocco. The tracheids in the two hybrids had a very high Runkel ratio (2 x cell wall thickness/lumen diameter) and produced kraft paper sheets with low tensile strength due to a low degree of fiber collapse thus a low relative bonded area. These fibers could be used to increase the stiffness of a papermaking furnish. The lignin in the EGC 39 chips was more reactive in kraft pulping as compared to the other two eucalypti. Methoxyl analyses and nitrobenzene oxidation (NBO) of the in-situ lignin (wood meals) were performed, and it was concluded that the syringyl content of the EGC 39 lignin was less than or equal to those in the other two eucalypti. Differences in the guaiacyl fraction of the three samples will be discussed in Part 2 of this series. PDF
Alves, E. F., Francis, R. C., Barcha, B., and El Moussaouiti, M. (2012). "Kraft pulping characteristics of three Moroccan eucalypti. Part 2. Comparison of the guaiacyl fraction of the native lignins by a novel method," BioRes. 7(2), 1569-1581.
In Part 1 of this series it was observed that one of the eucalypti (EGC 39) was more reactive than the other two in kraft and soda-AQ (SAQ) cooking. However, the lignin in EGC 39 contained equal or less syringyl (S) units than the other two eucalypti. In the present research an attempt was made to compare the guaiacyl (G) fraction of the three lignins. The approach was to use SAQ treatment to cleave β-O-4 bonds in dimeric units containing uncondensed guaiacyl A-rings (those rearranging to quinone methides). The coniferyl alcohol, vinylguaiacol and isoeugenol generated from β-O-4 cleavage are then trapped as dimers by ethylguaiacol that is included in the SAQ liquor. Research with sugar maple (Acer saccharum) showed that the estimate of these structures (uncondensed G-β-O-4) by this approach was in close agreement with traditional but more tedious methods such as permanganate oxidation and 31P NMR. It was also shown that the lignin in the EGC 39 hybrid contained a higher concentration of uncondensed G-β-O-4 structures than the other two eucalypti lignins. PDF
Thomsen, S. T., Jensen, M., and Schmidt, J. E. (2012). "Production of 2nd generation bioethanol from lucerne - Optimization of hydrothermal pretreatment," BioRes. 7(2), 1582-1593.
Lucerne (Medicago sativa) has many qualities associated with sustainable agriculture such as nitrogen fixation and high biomass yield. Therefore, there is interest in whether lucerne is a suitable biomass substrate for bioethanol production, and if hydrothermal pretreatment (HTT) of lucerne improves enzymatic convertibility, providing sufficient enzymatic conversion of carbohydrate to simple sugars for ethanol production. The HTT process was optimised for lucerne hay, and the pretreated biomass was assessed by carbohydrate analysis, inhibitor characterisation of liquid phases, and by simultaneous saccharification and fermentation (SSF) of the whole slurry with Cellubrix enzymes and Saccharomyces cerevisiae yeast. The optimal HTT conditions were 205°C for 5 minutes, resulting in pentose recovery of 81%, and an enzymatic convertibility of glucan to monomeric glucose of 74%, facilitating a conversion of 6.2% w/w of untreated material into bioethanol in SSF, which is equivalent to 1,100 litre ethanol per hectare per year. PDF
Chang, S. Y., Ismail, H., and Ahsan, Q. (2012). "Effect of maleic anhydride on kenaf dust filled polycaprolactone/ thermoplastic sago starch composites," BioRes. 7(2), 1594-1616.
The utilization of biodegradable polymers for various applications has been restricted mainly by its high cost. This report aims to study the water absorption and mechanical properties of kenaf dust-filled polycaprolactone/thermoplastic sago starch biodegradable composites as a function of filler loading and treatment with maleic anhydride. While water absorption in untreated biocomposites increased as a function of filler loading, treated biocomposites resulted in weight loss, whereby low molecular weight substances were dissolved into the aging medium. The kenaf dust imparts reinforcing effects on the biocomposites, resulting in improved mechanical properties. This is further attested by morphological studies in which kenaf dust was well dispersed in the polycaprolactone/ thermoplastic sago starch blend matrix. The addition of maleic anhydride into the polycaprolactone/thermoplastic sago starch blend resulted in a homogeneous mixture. At low filler loading, strain at break of the maleated polycaprolactone/thermoplastic sago starch blend increased at the expense of tensile strength and modulus. This is most likely due to the excessive dicumyl peroxide content, which caused chain scission of the polycaprolactone backbone. Tensile strength and modulus improved only when high filler loading was employed. PDF
Xue, B., and Hu, Y. (2012). "Mechanical properties analysis and reliability assessment of laminated veneer lumber (LVL) having different patterns of assembly," BioRes. 7(2), 1617-1632.
Laminated Veneer Lumber (LVL) panels made from poplar (Populus ussuriensis Kom.) and birch (Betula platyphylla Suk.) veneers were tested for mechanical properties. The effects of the assembly pattern on the modulus of elasticity (MOE) and modulus of rupture (MOR) of the LVL with vertical load testing were investigated. Three analytical methods were used: composite material mechanics, computer simulation, and static testing. The reliability of the different LVL assembly patterns was assessed using the method of Monte-Carlo. The results showed that the theoretical and ANSYS analysis results of the LVL MOE and MOR were very close to those of the static test results, and the largest proportional error was not greater than 5%. The veneer amount was the same, but the strength and reliability of the LVL made of birch veneers on the top and bottom was much more than the LVL made of poplar veneers. Good assembly patterns can improve the utility value of wood. PDF
Xu, M., Dai, H., Sun, X., Wang, S., and Wu, W. (2012). "Influence of buffer solution on TEMPO-mediated oxidation," BioRes. 7(2), 1633-1642.
TEMPO-mediated oxidation has been reported to effectively convert C6 primary hydroxyl groups to carboxyl groups for better water-solubility. However, the pH decreases continuously during the oxidation process, and it is therefore difficult to maintain the stability of the reaction. The control of pH at a constant level throughout the oxidation process is a complicated task. The applicability of a carbonate buffer system and a borax buffer system with various continuous addition rate of sodium hypochlorite solution was considered. Carbonate buffer solution and borax buffer solution can efficiently buffer the pH. The results of carboxyl content and DP of celluloses proved that the activities of sodium hypochlorite solution can be maintained when sodium hypochlorite is added with controlled flow rates without adjusting pH by hydrochloric acid. Buffer solutions created a milder reaction environment in which the damage of celluloses would be buffered. The conclusion was consistent with DP tests of celluloses. Compared with carbonate buffer, the borax buffer with high ability of penetration could enhance the depth and width of oxidation, which was demonstrated by the results of X-ray diffraction patterns and carboxyl content of celluloses. PDF
Tawakkal, I. S. M. A., Talib, R. A., Abdan, K., and Ling, C. N. (2012). "Mechanical and physical properties of kenaf-derived cellulose (KDC)-filled polylactic acid (PLA) composites," BioRes. 7(2), 1643-1655.
Kenaf-derived cellulose (KDC)-filled poly(lactic acid) (PLA) composites were prepared via melt blending and compression molding to improve the properties of PLA by introducing a natural cellulose that was chemically derived (chlorination and mercerization processes) from plant-based kenaf bast fibers. The effect of KDC content (0-60 wt.%) on the tensile elongation at the break point and during flexural and impact testing and on the water absorption and density of the composites was investigated, while the neat PLA polymer (without the addition of cellulose) served as a reference for the composites. The elongation at the break point of the composites was 9% on average, making it less elastic than the neat PLA. The flexural strength and modulus also increased by 36% and 54%, respectively. The impact strength of the composites was improved at KDC contents below 40 wt.%, but the impact strength was reduced above 40 wt.%. The composite containing the highest amount of KDC (60 wt.%) was denser than the neat PLA and had a water uptake of approximately 12%, which is notably low for a biocomposite system. PDF
Ozmen, N., and Yesilada, O. (2012). "Valorization and biodecolorization of dye adsorbed on lignocellulosics using white rot fungi," BioRes. 7(2), 1656-1665.
Biosorption of dyes by lignocelluloses may be an effective method for removing dyes from textile effluents. However, the resulting dye-adsorbed lignocellulosic materials may constitute another pollution problem. An integrated method can solve this problem. Here, various lignocelluloses were tested for their Astrazon Black and Astrazon Blue dyes removal activities. The dye adsorbed after 30 min contact time was 90% (45 mg/L), 70% (35 mg/L), and 98% (49 mg/L) for wheat bran, pine cone, and cotton stalk, respectively. These dye-adsorbed lignocellulosic wastes then were used as solid substrates to produce laccase enzyme with Funalia trogii and Trametes versicolor under solid state fermentation (SSF). Among the lignocellulosic substrates, the dye-adsorbed wheat bran served as the best solid substrate for laccase production under SSF. Therefore, it was also tested as a solid source for laccase production under submerged fermentation. During solid state fermentation, these two fungi were able to highly decolorize these dyes. While F. trogii decolorized 80% of Astrazon Black dye adsorbed onto wheat bran, T. versicolor decolorized 86%. On the other hand, the decolorization values for Astrazon Blue dye were 69% and 84%, respectively. PDF
Brodin, F. W., and Theliander, H. (2012). "Absorbent materials based on kraft pulp: Preparation and material characterization," BioRes. 7(2), 1666-1683.
Today, petroleum-based superabsorbents are widely used, but interest in renewable alternatives is on the rise. This study presents two wood-based absorbent materials suitable for various absorption applications as an alternative to petroleum-based products. Never-dried bleached kraft pulp was treated with TEMPO-oxidation, and new carboxylate and aldehyde groups were introduced. It was found that the aldehyde groups contributed to the wet integrity of the absorbent materials, possibly by the formation of hemiacetal bonds. After oxidation, the pulp fibers were gradually disintegrated, and size analysis showed that the disintegration rate was enhanced by an increase in the charge of the oxidant. Freeze drying produced a porous foam with a large surface area that enabled a rapid absorption rate as well as a reasonably high absorption capacity even for absorption under load. Air drying formed a compact film with a slow absorption rate but with a high final capacity for absorption. PDF
Jiang, J., Tong, G., and Chin, Y. F. (2012). "The effect of charge and chemical structure of cationic surfactants on laser toner agglomeration under alkaline pulping conditions," BioRes. 7(2), 1684-1696.
Laboratory-scale agglomeration experiments followed by image analysis were used to evaluate the effectiveness of different cationic surfactants on the 1-octadecanol agglomeration of a negatively charged laser toner. Various types of surfactants with different geometric structures were investigated. It was found that this toner became agglomerated under neutral pulping conditions, but it did not agglomerate under alkaline conditions at all. A small amount of the cationic surfactant compensated for the agglomeration disruption caused by the negative surface charge of the toner and made this toner agglomerate very well. These cationic surfactants consist of a chemical structure of C12 to C18 saturated alkyl hydrophobic chains. The positive charge of these surfactants played the major role in alleviating agglomeration disruption. Additionally, an extra phenol group on these surfactants contributed only minor advantages for toner agglomeration in the presence of 1-octadecanol. The best co-agglomeration performance occurred within a very narrow range of similar total positive charge densities based on the total toner weight. It was also found that this positive charge effect could not be applied to the chemical compounds of high molecular weight polymeric materials. PDF
Huang, F., Lanouette, R., and Law, K.-N. (2012). "Morphological changes of jack pine latewood and earlywood fibers in thermomechanical pulping," BioRes. 7(2), 1697-1712.
The morphological changes of jack pine (Pinus banksiama) earlywood (EW) and latewood (LW) in thermomechanical pulping (TMP) were studied by light microscopy and scanning electronic microscopy. The results indicate that: under the mechanical forces in refining, the EW fibres tend to separate in the P/S1 interface, while separation of the LW fibres takes place commonly in the P/S1 and S1/S2 regions. The thick-walled LW fibres exhibit much more external fibrillation than the thin-walled EW. As a result, the LW fines contain more fibrillar component than EW fines. The EW fibers suffer more fiber cutting and splitting than the LW fibers. In addition, the thin-walled EW fibres show higher collapsibility and conformability than the LW counterparts. PDF
Kataja-aho, J., Haavisto, S., Asikainen, J., Hyvärinen, S., and Vuoti, S. (2012). "The influence of cationized birch xylan on wet and dry strength of fine paper," BioRes. 7(2), 1713-1728.
Cationized birch xylan was prepared and its use as a papermaking chemical was evaluated. The focus was on studying the effects of cationized birch xylan on the wet and dry strength of fine paper. The results of the laboratory experiments show that the addition of 3 percent of cationized birch xylan to birch kraft pulp improved the initial wet strength of the web by 30 percent compared to base stock at a solids content of 55%. Furthermore, the tensile stiffness of the wet web increased by approximately a third and the dry tensile strength improved by 26%, while the dry elastic modulus was not changed. The improvements in the strength properties were clear when compared to the base stock, but not as high as achieved with conventionally used cationized starch. The difference between the xylan and starch is most likely due to the shorter polymer chain length of the cationized xylan. PDF
Olek, W., and Bonarski, J. T. (2012). "Influence of cyclic sorption on wood ultrastructure," BioRes. 7(2), 1729-1739.
Desorption and adsorption cycles result in dimensional changes of wood. The shrinkage and swelling of wood components are accompanied by the forming and breaking of bonds at sorption sites of water molecules. These processes may lead to some reorganization of the wood ultrastructure. The traditionally applied crystallographic descriptors, i.e. the mean microfibril angle and crystallinity, are unable to quantify such ultrastructural changes. The crystallographic texture analysis was performed to account for the reorganization of wood ultrastructure during the cyclic sorption. The Orientation Distribution Function (ODF) was separately calculated for the selected sorption cycles. Inverse pole figures, texture index, crystalline volume fraction, and integrated skeleton lines of the ODF made a set of crystallographic descriptors used to study the ultrastructural changes within this study. The registered reorganization of the ultrastructure was manifested in changes of the intensities of the individual texture components, including the disappearance of some components. However, the texture index, being the global measure of the crystallographic texture, was practically constant during the cycling sorption. PDF
Jahan Latibari, A. (2012). "Extended delignification of old corrugated container and totally chlorine free bleaching of the pulp," BioRes. 7(2), 1740-1747.
The paper industry has taken various steps to address environmental concerns and raw material limitations. Among them, paper recycling has been shown to be a viable option. In this study, the alkaline sulfite pulping of old corrugated containers (OCC) to produce bleachable pulp was investigated. A combination of one of the three active alkali levels (14, 16, and 18%; Na2O, and oven-dry weight of OCC); one of two pulping temperatures (145 and 175ºC), and one of two pulping times (60 and 120 minutes) and sodium sulfite to sodium hydroxide ratio of 30/70 (mol/mol) were examined. After preliminary pulping and evaluation, pulp with a kappa number of 18.3 and brightness of 50.2%, which was produced applying 18% active alkali, sodium sulfite to sodium hydroxide ratio of 30:70, and pulping time and temperature of 120 minutes and 175ºC, respectively, having the yield of 64.0% (based on oven dry weight of washed OCC) and 72.7% (based on original weight of the OCC as received), respectively, was selected for totally chlorine free (TCF) bleaching trials. Brightness, opacity, tensile, and tear strength indices of this pulp were measured as 50.2%, 81.4%, 27.7 N.m/g, and 12.35 mN.m2/g, respectively. Bleaching of this pulp applying 3% H2O2 and 2.25% NaOH at 90 minutes generated bleached pulp with brightness and opacity as 57.1% and 78.2%, respectively. The bleaching yield was measured as 92%. Tensile and tear strength indices of this pulp were measured as 25.1 Nm/g and 12.4 mN.m2/g, respectively. PDF
Xiao, S., Yuan, T., Cao, H., Lin, D., Shen, Y., He, J., and Wang, B. (2012). "Synthesis and characterization of cellulose-graft-poly(L-lactide) via ring-opening polymerization," BioRes. 7(2), 1748-1759.
Cellulose-graft-poly (L-lactide) (cellulose-g-PLLA) was prepared under homogeneous mild conditions. Ring-opening polymerization (ROP) was carried out successfully using 4-dimethylaminopyridine (DMAP) as an organic catalyst in an ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl). The structure of the polymer was characterized by GPC, 1H NMR, 13C NMR, FT-IR, TGA, WAXD, and AFM. The results indicated that the grafting rate of the polymer reached 4.44, which was higher than that reported in AmimCl with Sn(oct)2 as a catalyst. In addition, AFM showed that the polymer in solution could aggregate and self-assemble into an approximately spherical structure, which was different from the rod-like structure of cellulose and round-like polylactic acid particles. PDF
Pan, M., Mei, C., and Song, Y. (2012). "A novel fire retardant affects fire performance and mechanical properties of wood flour-high density polyethylene composites," BioRes. 7(2), 1760-1770.
Wood flour-high density polyethylene (HDPE) composites were prepared to investigate the effects of ammonium polyphosphate based fire retardant content (2, 4, 6, 8, and 10-wt%), on the flammability, mechanical, and morphological properties of the wood flour-HDPE composites in this study. Cone calorimetry analysis showed that the addition of fire retardant could decrease the heat release rate (HRR) and total smoke release of wood flour-HDPE composites, while it had no obviously effects on effective heat of combustion. Most of the decrease of the HRR occurred with the concentration of the fire retardant up to 4-wt%. With addition of fire retardant, the composites showed a decrease in tensile elongation at break and impact strength, and had no obvious effect on tensile and flexural strength. The scanning electron microscopy observation on the fracture surface of the composites indicated that fire retardant had a uniform dispersion in the wood flour-HDPE composites. However, interfacial bonding would be suggested to improve in wood flour-HDPE composites with ammonium polyphosphate based fire retardant. PDF
Sable, I., Grinfelds, U., Jansons, A., Vikele, L., Irbe, I., Verovkins, A., and Treimanis, A. (2012). "Comparison of the properties of wood and pulp fibers from lodgepole pine (Pinus contorta) and Scots pine (Pinus sylvestris)," BioRes. 7(2), 1771-1783.
In this study, the relationship between the properties of the wood and kraft pulp fibers as well as paper characteristics of 27-year-old trees, lodgepole pine (Pinus contorta) and Scots pine (Pinus sylvestris), was assessed. All trees had been grown in Latvia, within the same forest type, Myrtillosa. Wood density, year ring width, chemical composition and cross-sectional cell wall dimensions were measured. Fiber characteristics were determined, and handsheets were made for all samples from unbeaten kraft pulp. The results showed that the amount of latewood had a positive correlation with wood density for both species and with further positive impact on the paper burst index. Also, slight differences in cross-sectional dimensions were observed. Lodgepole pine provided paper with higher burst strength than Scots pine. Since the former is of higher density, less wood per volume is needed to produce a ton of pulp, and results showed a higher pulp yield in the case of lodgepole pine. PDF
Kamal Bahrin, E., Samsu Baharuddin, A., Ibrahim, M. F., Abdul Razak, M. N., Sulaiman, A., Abd-Aziz, S., Hassan, M. A., Shirai, Y., and Nishida, H. (2012). "Physicochemical property changes and enzymatic hydrolysis enhancement of oil palm empty fruit bunches treated with superheated steam," BioRes. 7(2), 1784-1801.
The effect of superheated steam treatment on oil palm empty fruit bunches (OPEFB) was investigated in terms of physicochemical property changes and enzymatic hydrolysis enhancement. The experimental treatment was carried out at different temperatures (140-210°C) and durations (20-90 min). Results showed that as the superheated steam temperature and time increased, the size distribution also changed, resulting in more small particles. Analysis on the surface texture, color, and mechanical properties of the treated OPEFB also showed that significant changes resulted due to the superheated steam treatment. In support to this, Fourier Transform Infrared (FTIR) spectroscopy and thermogravimetric (TG) analyses showed that solubilization and removal of the hemicelluloses component also took place. As a result of this phenomenon, higher total sugar and glucose yield was achieved once the treated OPEFB was subjected to enzymatic hydrolysis. This suggests that superheated steam treatment could enhance OPEFB structure degradation for the preparation of a suitable substrate in order to produce a higher glucose yield in the enzymatic hydrolysis process. PDF
Yu, M., Yang, R., Huang, L., Cao, X., Yang, F., and Liu, D. (2012). "Preparation and characterization of bamboo nanocrystalline cellulose," BioRes. 7(2), 1802-1812.
Nanocrystalline cellulose (NCC) has many potential applications because of its special properties. In this paper, NCC was prepared from bamboo pulp. Bamboo pulp was first pretreated with sodium hydroxide, followed by hydrolysis with sulfuric acid. The concentration of sulfuric acid and the hydrolysis time on the yield of NCC were studied. The results showed that sulfuric acid concentration had larger influence than the hydrolysis time on the yield of NCC. When the temperature was 50oC, the concentration of sulfuric acid was 48wt% and the reaction time was 30 minutes, a high quality of nanocrystalline cellulose was obtained; under these conditions, the length of the nanocrystalline cellulose ranged from 200 nm to 500 nm, the diameter was less than 20 nm, the yield was 15.67wt%, and the crystallinity was 71.98%, which is not only higher than those of cellulose nanocrystals prepared from some non-wood materials, but also higher than bamboo cellulose nanocrystals prepared by other methods. PDF
Lehto, J., and Alén, R. (2012). "Purification of hardwood-derived autohydrolysates," BioRes. 7(2), 1813-1823.
Carbohydrate-containing hydrolysates (1.1 to 14.9% of wood dry matter) obtained from autohydrolysis (at 130 to 150°C for 30 to 120 minutes) of birch (Betula pendula) chips prior to pulping were purified with respect to non-carbohydrate materials, without carbohydrate losses, either by ethyl acetate extraction or XAD-4 resin treatment. In the former case, about 50% of lignin and practically all the furanoic compounds (2-furaldehyde and 5-(hydroxymethyl)furfural) could be removed, whereas in the latter case, the corresponding amounts were about 30% and 50 to 90%, respectively. A partial recovery of various unsaturated impurities is of importance, because they may act as inhibitors when biochemically converting carbohydrates in hydrolysates into value-added products. PDF
Raspolli Galletti, A. M., Antonetti, C., De Luise, V., Licursi, D., and Nassi o Di Nasso, N. (2012). "Levulinic acid production from waste biomass," BioRes. 7(2), 1824-1835.
The hydrothermal conversion of waste biomass to levulinic acid was investigated in the presence of homogeneous acid catalysts. Different cheap raw materials (poplar sawdust, paper mill sludge, tobacco chops, wheat straw, olive tree pruning) were employed as substrates. The yields of levulinic acid were improved by optimization of the main reaction parameters, such as type and amount of acid catalyst, temperature, duration, biomass concentration, and electrolyte addition. The catalytic performances were also improved by the adoption of microwave irradiation as an efficient heating method, allowing significant energy and time savings. The hydrothermal conversions of inulin and wheat straw were carried out in the presence of niobium phosphate, which up to now have never been employed in these reactions. The preliminary results appeared to be in need of further optimization. PDF
Flandez, J., González, I., Resplandis, J. B., El Mansouri, N.-E., Vilaseca, F., and Mutjé, P. (2012). "Management of corn stalk waste as reinforcement for polypropylene injection moulded composites," BioRes. 7(2), 1836-1849.
The main objective of this study was the management of corn stalk waste as reinforcement for polypropylene (PP) injection moulded composites as an alternative to wood flour and fibers. In the first step, corn stalk waste was subjected to various treatments, and four different corn stalk derivatives (flour and fibers) able to be used as reinforcement of composite materials were prepared and characterized. These derivatives are corn stalk flour, thermo-mechanical, semi-chemical, and chemical fibers. They were characterized in terms of their yield, lignin content, Kappa number, fiber length/diameter ratio, fines, coarseness, viscosity, and the length at the break of a standard sheet of paper. Results showed that the corn stalk derivatives have different physico-chemical properties. In the second step, the prepared flour and fibers were explored as a reinforcing element for PP composites. Coupled and non-coupled PP composites were prepared and tested for tensile properties. For overall trend, with the addition of a coupling agent, tensile properties of composites significantly improved, as compared with non-coupled samples. In addition, a morphological study revealed the positive effect of the coupling agent on the interfacial bonding. The composites prepared with semichemical fiber gave better results in comparison with the rest of the corn stalk derivatives due to its chemical characteristics. PDF
dos Santos, C. M. T., Del Menezzi, C. H. S., and de Souza, M. R. (2012). "Properties of thermo-mechanically treated wood from Pinus caribaea var. hondurensis," BioRes. 7(2), 1850-1865.
This study aimed at evaluating the effect of thermo-mechanical treatment on properties of Pinus caribaea var. hondurensis wood.Two pressure levels (25% and 50% of the compression strength perpendicular to grain) were evaluated. The treatment was applied in a laboratory hot press in one-step or two-step modes for 50 minutes. In the one-step treatment, the total pressure was applied after the temperature of the center of the wood reached 170°C. In the two-steps treatment, half of the pressure was applied after the center of the wood reached 100°C, and the final pressure was applied when it reached 170°C. The weight loss immediately after treatment was equivalent to the wood moisture content, indicating that degradation of wood polymers did not occur. However, the treatments showed decreasing values of the moisture content, which were reduced from 12.3% to 9.8%. A moderate improvement on surface roughness was achieved, while wood wettability was highly reduced in all treatments, as determined by contact angle measurement. On the other hand, the treatment applied did not improve the wood dimensional stability, but all mechanical properties presented a trend of improvement. PDF
Ma, X., Huang, L., Cao, S., Chen, Y., Luo, X., and Chen, L. (2012). "Preparation of dissolving pulp from bamboo for textile applications. Part 2. Optimization of pulping conditions of hydrolyzed bamboo and its kinetics," BioRes. 7(2), 1866-1875.
Kraft pulping of hydrolyzed green bamboo (Dendrocalamopsis oldhami) chips was performed under various conditions to determine the effects of process variables (alkali charge, sulfidity, cooking temperature, and cooking time) on the dissolution of the lignocellulosic components, i.e. lignin, pentosans, and cellulose. Meanwhile, the kinetics of kraft delignification of hydrolyzed bamboo was investigated. The results showed that both an increase of alkali charge and sulfidity could result in a clear reduction in kappa number and yield, but the effect of alkali charge was more significant than that of sulfidity. Even though severe conditions were able to purify fiber, the cellulose degradation occurred intensively. Active alkali charge 23%, sulfidity 26%, cooking temperature 170°C, and cooking time 60 min were selected as the optimum conditions for the consideration of selective delignification. As a consequence, the properties of the pulp produced at optimum cooking conditions were determined to be: kappa number 6.3, pentosans 5.0%, a-cellulose 90.2%, and viscosity 30.3 mPa·s. The data analysis confirmed that the reaction order of delignification was approximate to 1.1, and the activity energy of the hydrolyzed bamboo was 53 kJ/mol. PDF
Li, M.-F., Sun, S.-N., Xu, F., and Sun, R.-C. (2012). "Benzylation and characterization of cold NaOH/urea pre-swelled bamboo," BioRes. 7(2), 1876-1890.
Ball-milled bamboo was pre-swelled with a cold aqueous solution of NaOH and urea, and then reacted directly with benzyl chloride to synthesize benzylated bamboo. The effects of the molar ratio of benzyl chloride to OH groups in the bamboo (1 to 4), the reaction temperature (70 to 110 °C), and the reaction time (2 to 8 h) on both the product yield and the degree of substitution (DS) were evaluated. Yields between 67.6 and 94.0% and DS between 0.31 and 0.74 of the benzylated bamboo were obtained under such conditions. The incorporation of benzyl groups was evidenced by FT-IR and CP/MAS 13C-NMR spectroscopy. It was found that the crystalline structure of the native ball-milled bamboo was markedly damaged after modification. In addition, the benzylated bamboo was subjected to thermal degradation at a high temperature with an increase in substitution. It was suggested that the benzylated bamboo with a low crystallinity as well as large non-polar groups is promising as a filler for use in the composite material industry. PDF
Ratsamee, S., Akaracharanya, A., Leepipatpiboon, N., Srinorakutara, T., Kitpreechavanich, V., and Tolieng, V. (2012). "Purple guinea grass: Pretreatment and ethanol fermentation," BioRes. 7(2), 1891-1906.
Treatment with dilute sulfuric acid (H2SO4) or calcium hydroxide (Ca(OH)2) at 121°C and 103.4 kPa was used to improve the efficiency of the cellulose digestion of purple guinea grass. Cellulase hydrolysis of the dilute H2SO4-pretreated purple guinea grass under optimized conditions (6% (w/v) in 3% (w/v) H2SO4 for 30 min) yielded a slightly higher level of reducing sugars than that from the Ca(OH)2 pretreatment under optimized conditions (6% (w/v) in 4% (w/v) Ca(OH)2 for 5 min). However, the level of glucose released from the Ca(OH)2-pretreated purple guinea grass was slightly higher than that from the dilute H2SO4 pretreatment. Ethanol fermentation, via the separate hydrolysis and fermentation (SHF) process using Saccharomyces cerevisiae, of the Ca(OH)2-pretreated purple guinea grass and then hydrolyzed with commercial cellulase (9 PFU/g, dry wt.) for 6 h yielded ethanol at 0.44 g/g glucose (0.21 g/g cellulose) within 48 h, while that from the simultaneous saccharification and fermentation process yielded 14.3% less ethanol at 0.18 g/g cellulose within 96 h (including the 6 h saccharification time). The ethanol yield from the SHF process increased 1.14-fold to 0.497 g/g glucose (0.24 g/g cellulose) when the fermentation was performed in a 5 L fermentor. PDF
Dashti, H., Tarmian, A., Faezipour, M., Hedjazi, S., and Shahverdi, M. (2012). "Effect of pre-steaming on mass transfer properties of fir wood (Abies alba L.), a gymnosperm species with torus margo pit membrane," BioRes. 7(2), 1907-1918.
In this research, the effect of pre-steaming on mass transfer properties, including air permeability and water vapor diffusivity of fir wood (Abies alba L.), a gymnosperm species with torus margo pit membrane, was evaluated. The pre-steaming was performed at temperatures of 120, 140, and 160°C for 1 hour under a pressure of 2-3 bars. Then, the pre-steamed specimens were conventionally dried at a constant temperature of 160°C and a relative humidity of 50% to the final moisture content of 10%. Subsequently, the mass transfer properties of the dried specimens were measured in longitudinal and radial directions. Overall, the pre-steaming was found to be an effective modification method to improve the mass transfer properties of Abies alba L. The improvement was more remarkable for the air permeability as well as through the radial direction. The specimens steamed at the temperature of 160°C had higher mass transfer rates than those steamed at the temperatures of 120 and 140°C. Results of chemical analyses, FT-IR spectroscopy, and SEM imaging provide some explanations for the effects of pre-steaming. PDF
Hua, J., Chen, G., Xu, D., and Shi, S. Q. (2012). "Impact of thermomechanical refining conditions on fiber quality and energy consumption by mill trial," BioRes. 7(2), 1919-1930.
Fiber thermomechanical refining is a critical step for the manufacturing of medium density fiberboard (MDF). To increase productivity and improve fiber quality with a reduction in energy consumption during refining, it is essential to determine appropriate refining conditions, such as the chips retention time (accumulated chip height, CH) in the pre-heater, feeding screw revolution speed (SR) in the chip feeding pipe, and the opening ratio of the discharge valve (OV) in the discharge pipe. Using multiple regression analysis, relationships between the response variables (the total fibers, the specific energy consumption obtained by the motor power consumption/the total amount of dry fibers, and the percentage of qualified fibers) and the predictor variables (OV, CH, and SR) were modeled. Specific energy consumption decreased with an increase in CH. When more chips were stored in the pre-heater, the chips were softened by the extended steam-treatment time, reducing the energy consumption. There were negative relationships between the percentage of qualified fibers and the predictor variables (OV and SR). It was reasoned that a greater proportion of coarse fibre was produced when the discharge valve opening ratio or the feeding screw speed increased. This resulted in a reduction in the percentage of qualified fibers. Due to the large sample size (1667 measurements for each variable) in this study, the resulting regression equations can be applied to estimate the productivity, energy consumption, and fiber quality during refining in an MDF mill. PDF
Deteix, J., Djoumna, G., Blanchet, P., Fortin, A., and Cloutier, A. (2012). "Minimizing flooring strip weight: A shape optimization approach," BioRes. 7(2), 1931-1947.
In North America, flooring strips are manufactured with grooves at the back. There are various reasons for these grooves but, historically, they were considered a strategy to reduce weight and transportation costs as well as improving dimensional stability. As no data are available to assess best practices in terms of performance, we have investigated methods to reduce flooring strip weight. One way to achieve this is to adjust the number and shape of grooves. Using warp as a comparison tool, we were able to analyze the merits of a finite number of designs. With this approach, however, we could not guarantee that the result was the most favourable. The search for a solution led to design optimization, i.e.: minimizing weight by acting upon a part of the strip's shape, taking into account its warp resistance or stiffness. This paper describes an optimization strategy adapted to the calculation of the optimal design subjected to arbitrary mechanical and geometrical conditions (including the thickness of the wear layer). This approach is not limited to flooring strips, and it can be used in any situation where a linear hygromechanical model is relevant. This strategy involves two steps: global optimization with respect to admissible variations of the shape (or design) followed by a post-processing phase that takes into account various other mechanical and possibly geometrical conditions imposed on the strip. PDF
Bernal-Vicente, A., Ros, M., and Pascual, J. A. (2012). "Inoculation of Trichoderma harzianum during maturation of vineyard waste compost to control muskmelon Fusarium wilt," BioRes. 7(2), 1948-1960.
The utilization of compost vineyard wastes as suppressive growing media against Fusarium wilt is a good alternative for the disposal and recycling of these organic wastes. Inoculation of biological control agents (BCAs) enhances the biocontrol activity of compost. In this experiment, vineyard compost was sampled at different stages during the composting process, rating the values of acceptability for growing media. Under greenhouse nursery conditions, composts inoculated with Trichoderma harzianum T-78, (Th T-78) gave higher plant fresh weights, as well as lower pathogen incidence and disease severity than treatments with Th T-78 inoculated at muskmelon sowing and non-inoculated composts. Comparing the two composts inoculated with Th T-78 at different stages of the composting process, the one inoculated at the beginning of maturation phase showed lower pathogen incidence and disease severity than the one inoculated at the beginning of the composting process. PDF
Li, J., Rao, X., Shang, S., Gao, Y., and Song, J. (2012). "Synthesis and antibacterial activity of amide derivatives from acrylopimaric acid," BioRes. 7(2), 1961-1971.
This paper reports on the synthesis of a series of amide derivatives from acrylopimaric acid (APA). The derivatives contained aromatic groups and were characterized by IR, 1HNMR, MS, and elemental analysis. The antibacterial activity of the derivatives against Gram-negative bacteria and Gram-positive bacteria were also investigated. When compared with the other derivatives, compounds 3a and 3f showed much higher activity against Escherichia coli (Gram-negative bacteria) with inhibition zones of 5 mm and 5.5 mm, respectively. Structure-activity relationship analysis revealed that ortho-substituted phenyl derivatives and meta-substituted phenyl derivatives exhibited higher activity than the para-substituted derivatives. Meanwhile, the halogen-substituted compounds did not show visible antibacterial activity compared with other compounds, which may have been caused by the lower electron density of the halogen-substituted phenyl rings. PDF
Wang, W., Zhao, Z., Gao, Z., and Guo, M. (2012). "Water-resistant whey protein based wood adhesive modified by post-treated phenol-formaldehyde oligomers (PFO)," BioRes. 7(2), 1972-1983.
With the attempt to develop an environmentally safe whey protein-based adhesive with good water resistance, a low-molecular-weight PFO was used as a modifier, and the effects of scavengers on the formaldehyde emission and bond properties were investigated. Plywood evaluation and HPLC analysis indicated that the PFO synthesized with a low content of sodium hydroxide as a catalyst (NaOH/phenol mole ratio = 0.064) at a low reaction temperature (60-75oC) had good water solubility and very low viscosity that was preferable to the modification of whey protein-based adhesives. Combinations of ammonia and sodium sulfite as formaldehyde scavengers had positive effects on the formaldehyde emissions of plywood panels bonded by the PFO-modified whey protein adhesives and had slight effects on bond properties. A necessary stoichiometric excess of ammonia-sulfite combination during PFO post-treatment is critical to effectively reduce formaldehyde emission. The whey protein-based adhesive modified with the most preferable post-treated PFO is water-resistant and environmentally safe, which had a dry shear bond strength of 1.98 MPa and a 28 hour-boiling-dry-boiling wet shear strength of 1.73 MPa according to standard JIS K6806-2003, a formaldehyde emission of 0.067mg/L according to standard JIS A5908, and undetectable level of free phenol by HPLC. PDF
Kadimaliev, D., Telyatnik, V., Revin, V., Parshin, A., Allahverdi, S., Gunduz, G., Kezina, E., and Asik, N. (2012). "Optimization of the conditions required for chemical and biological modification of the yeast waste from beer manufacturing to produce adhesive compositions," BioRes. 7(2), 1984-1993.
During the production of beer large amounts of yeast waste are generated. This paper considers the possible making of environmentally friendly adhesive compositions from such wastes. Chemical treatment of yeast wastes increases their adhesive characteristics. Chemical cross-linking with glutaric aldehyde and biological cross-linking by enzyme transglutaminase improves the moisture resistance of the adhesive compositions. In terms of their physical and mechanical parameters they are not inferior to glues of natural origin and can be used for bonding paper, cardboard, and wood. The bonding strength of paper was 421.8 N / m, and that of wood was 27.8 MPa. PDF
Dougherty, D., and Wright, J. (2012). "Silviculture and economic evaluation of eucalypt plantations in the southern US," BioRes. 7(2), 1994-2001.
Demand for hardwood from plantation-grown stands for pulp and bio-energy in the southern US is more than 90 million tons per year and is increasing. In the specific case of bio-energy and pulp, demand for biomass from eucalypts could approach 20 million tons/year by the year 2022. Fast growing species and hybrids of Eucalyptus are being evaluated to partially fill this demand gap. Though widely grown in a number of countries for pulp as well as for bio-energy, eucalypts in the southern US have not been extensively researched. Initial growth rates of 18 to 36 green tons/ha/year on rotation lengths of 6 to 8 years are possible. Current estimated costs for energy production from eucalypts in the Southern US are estimated at $3.10 to $3.49 per MBtu, where landowner required return rates on reforestation capital invested range from 6 to 14 percent. Eucalypts as a bio-energy feedstock can be competitive with coal in cost per BTU in the southern US. PDF
El Ghali, A., Ben Marzoug, I., Baouab, M. H. V., and Roudesli, M. S. (2012). "Separation and characterization of new cellulosic fibres from the Juncus acutus L plant," BioRes. 7(2), 2002-2018.
Cellulose fibres from the Juncus acutus L plant were isolated and characterized. The isolation of the fibres was performed by sequential NaOH treatment and H2O2 bleaching under different extraction conditions. The chemical and surface morphological structures of the Juncus acutus L fibres were characterized with FTIR, SEM, AFM, DSC, surface energy, diameter, density, and lignin content determination. Changes in structure and properties of the obtained fibres were observed by varying the concentration and the treatment time of the applied process. Results revealed that the optimum conditions to remove most of non-cellulosic materials from the Juncus acutus L plant were 7M NaOH, 3h and 100°C for alkaline procedure, and 10 mL.L-1 H2O2, 45 minutes and 95°C for bleaching treatment. PDF
Singha, A. S., and Rana, A. K. (2012). "A comparative study on functionalization of cellulosic biofiber by graft copolymerization of acrylic acid in air and under microwave radiation," BioRes. 7(2), 2019-2037.
Graft copolymerization of Grewia optiva fiber with acrylic acid (AAc) was carried out by using a Ce(IV) redox initiator under two different conditions, i.e. in air and under the influence of microwave radiation. Different reaction conditions affecting grafting percentage (Pg) for both methods were optimized and compared. Optimized reaction parameters for maximum Pg (7.86%) for graft copolymerization of AAc onto Grewia optiva fiber in air were 90 min reaction time, a temperature of 45° C, 1.82X10-2 mol/L CAN, 2.88X10-1 mol/L nitric acid, and 3.50X10-1 mol/L AAc. However, the maximum Pg (5.56%) for graft copolymerization in the case of MWR were 15 min reaction time, 110 W power, 2.73X10-2 mol/L CAN, 2.88X10-1 mol/L nitric acid, and 2.91X10-1 mol/L AAc. Both raw and graft copolymerized fibers were subjected to the evaluation of some of their properties such as swelling, moisture absorbance, and chemical resistance behavior. The AAc-graft copolymerized Grewia optiva showed 19.23% more swelling when compared with that of raw fiber. Further morphological and structural changes, thermal stability, and the crystallanity of raw, Grewia optiva-g-poly(AAc) in air, and Grewia optiva-g-poly(AAC) under MWR fibers were also studied by SEM, FTIR, TGA, and XRD techniques. PDF
Téllez-Téllez, M., Díaz-Godínez, G., Aguilar, M. B., Sánchez, C., and Fernández, F. J. (2012). "Description of a laccase gene from Pleurotus ostreatus expressed under submerged fermentation conditions," BioRes. 7(2), 2038-2050.
In this work, a gene (lacP83) encoding a Pleurotus ostreatus laccase isoenzyme expressed in submerged fermentation conditions is described. A 2,887 bp sequence was obtained from a genomic library of P. ostreatus by using a PCR inverse strategy. The coding sequence, 1,527 bp long, showed 17 exons and encoded a protein of 509 amino acids, with a putative signal peptide and conserved copper binding domains. The promoter region of the lacP83 gene (466 bp upstream of ATG) contains putative binding transcription factors such as MRE, XRE, a defense response element, and a stress response element. The protein and gene sequences of lacP83 showed, respectively, 90 to 96% and 78 to 92% of similarity to laccases of Pleurotus previously reported. However, it showed differences in its apparent molecular weight and promoter sequence. PDF
Jedvert, K., Saltberg, A., Lindström, M. E., and Theliander, H. (2012). "Mild steam explosion and chemical pre-treatment of Norway spruce," BioRes. 7(2), 2051-2074.
The aim of this work is to open up the structure of wood while retaining a large amount of hemicelluloses, in particular (galacto)glucomannans. The effects of pre-treatments on wood meal from spruce (Picea abies) with a reducing agent (NaBH4) combined with steam explosion at very mild conditions were investigated. The effects of steam explosion at 160 °C were studied for various residence times (5 to 35 min) on both water-impregnated wood meal and samples pre-treated with NaBH4. The findings showed that pre-treatment with sodium borohydride stabilized the reducing end-groups of glucomannans and that the treatment was effective both during mild steam explosion, for both long and short residence times, as well as during subsequent treatment in alkali. Extraction experiments at different pH and temperatures showed that the main part of the hemicelluloses still remained in the wood residue after treatment. The molecular weight distributions of the extracted material from the liquors indicated that there were broad molecular distributions and that the molecular weight averages were between 3 and 6 kDa. PDF
Galván, M. V., Mocchiutti, P., Cornaglia, L. M., and Zanuttini, M. A. (2012). "Dual-polyelectrolyte adsorption of poly(allylamine hydrochloride) and xylan onto recycled unbleached kraft pulps," BioRes. 7(2), 2075-2089.
The effects of a double polyelectrolyte adsorption of poly(allylamine hydrochloride) (PAH) and xylan (Xyl) on a recycled unbleached softwood kraft pulp were studied. The kinetics of PAH adsorption on this pulp was analyzed by building adsorption isotherms and by estimating the surface nitrogen adsorbed through the X-ray photoelectron spectroscopy (XPS) technique. It was found that at pH 7.5, 0.01N NaCl, and short adsorption time, PAH is mainly adsorbed on the fiber surface. Adsorption isotherms of xylan on untreated and on previously PAH-treated pulps at different ionic strengths were built, and the effects of the amount of PAH on xylan adsorption were considered. It was found that when ionic strength was lower than 0.01N NaCl, a PAH pretreatment was necessary to achieve high levels of xylan adsorption at room temperature and short adsorption times. Nevertheless, when ionic strength was 0.1N NaCl, 0.3% xylan on pulp could be directly adsorbed on untreated pulp. Finally, it is shown that the dual-polyelectrolyte adsorption on this pulp is a feasible technique for improving paper tensile strength. PDF
Awada, H., Monplaisir, D., and Daneault, C. (2012). "Growth of polyelectrolyte on lignocellulosic fibres: Study by zeta potential, FTIR, and XPS," BioRes. 7(2), 2090-2104.
A layer-by-layer (LbL) self-assembly technique using polyallylamine hydrochloride (PAH) and polyacrylic acid (PAA) was employed to build up polyelectrolyte multi-layers on pretreated thermomechanical pulp fibres. These pretreated fibres previously had been oxidized by means of a 4-acetamido TEMPO-mediated process in order to create carboxylic functions. These allow the subsequent formation of amide bonds between PAH and fibres. X-ray photo-electronic spectroscopy (XPS) analyses confirmed the formation of amide bonds between the carboxylic function on the fibres and the primary amine function of the PAH. Besides, the surface charge intensity of the coated fibres was determined by measuring the zeta potential after each treatment step. PDF
Luís, Â., Gil, N., Amaral, M. E., Domingues, F., and Duarte, A. P. (2012). "Ailanthus altissima (Miller) Swingle: A source of bioactive compounds with antioxidant activity," BioRes. 7(2), 2105-2120.
Ailanthus altissima (Miller) Swingle is a tree used in Chinese traditional medicine as a bitter aromatic drug and in the treatment of colds and gastric diseases. Previous phytochemical studies have demonstrated the presence of quassinoids in the plant, as well as indole alkaloids. The purpose of this work was to determine the phenolic, flavonoid, and total alkaloid contents of the ethanolic, methanolic, acetone, and hydroalcoholic crude extracts of A. altissima and then try to correlate them with antioxidant activity of corresponding extracts. Moreover, the phenolic compounds present in the extracts were analyzed by RP-HPLC. Extracts from leaves have greater phenolic content than the other parts of this tree. Concerning the extraction process, it is possible to conclude that the mixture of water and ethanol is the best solvent to extract substances with antioxidant activity. Analysis by RP-HPLC showed that ferulic acid was the most dominant hydroxycinnamic acid, with an occurrence percentage of 25.59%. These results presented a positive linear correlation between antioxidant activity index and total phenolic content of all the extracts. PDF
Liu, J., Hu, H., Xu, J., and Wen, Y. (2012). "Optimizing enzymatic pretreatment of recycled fiber to improve its draining ability using response surface methodology," BioRes. 7(2), 2121-2140.
A three-factor, three-level Box-Behnken Design (BBD) was used with enzyme dosage (0.05-0.15‰ o.d. fiber), enzymatic contact time (20-40 min), and pulp consistency (3-7%, o.d.) as independent variables to understand and optimize the enzymatic pretreatment conditions of mixed office waste (MOW) for maximum improvement of its drainability. All the independent variables considered were found to have significant influence on the drainability of the pulp. The enzyme dosage had a predominate effect, the pulp consistency took second place, and the contact time seemed to have low priority. A quadratic polynomial model had high Adj-R2 value and low p value for predicting the decrement of beating degree of the pulp. Applying desirability function method, the optimal pretreatment conditions were found to be an enzyme dosage of 0.11‰ o.d., enzymatic contact time of 31.0 min, and pulp consistency of 4.50% o.d. The optimal pretreatment resulted in a maximum decrement of 10 units of beating degree, a decrease by 20% when compared with the control sample. The observed and predicted values of beating degrees were in close agreement. Results of fiber morphology analysis and physical property tests showed that the optimal pretreatment partially recovered the fiber flexibility and retained the strength properties of the handsheet even under the lower beating degree. Isothermal (Thermogravimetric Analyzer) TGA experiments of the fibers confirmed that the enzymatic pretreatment decreased the fiber hornification. PDF
Su, P., Granholm, K., Pranovich, A., Harju, L., Holmbom, B., and Ivaska, A. (2012). "Metal ion sorption to birch and spruce wood," BioRes. 7(2), 2141-2155.
Sorption of metal ions from aqueous solutions to birch wood and spruce heartwood and sapwood has been studied. Functional groups in wood were determined by acid-base titrations. The sorption of metal ions to wood of the different tree species was investigated by a column chromatographic technique. The mechanism of sorption is mainly ion exchange by complexation of metal ions to the functional groups, e.g. carboxyl groups and phenolic hydroxyl groups, in the wood phase. By combination of the sorption experiments with four different metal ion mixtures, the following affinity order was established for spruce sapwood particles: Fe3+>>Pb2+>>Cu2+>>Fe2+>Cd2+>Zn2+>Ni2+>Mn2+≥Ca2+≥Sr2+≥
Visakh, P. M., Thomas, S., Oksman, K., and Mathew, A. P. (2012). "Effect of cellulose nanofibers isolated from bamboo pulp residue on vulcanized natural rubber," BioRes. 7(2), 2156-2168.
Nanocomposites were prepared using two bioresources, viz., cellulose nanofibers (CNFs) extracted from bamboo paper-pulp waste as the reinforcing phase and natural rubber (NR) as the matrix phase. CNFs with diameters up to 50 nm were isolated from bamboo pulp waste, and nanocomposites with 5 and 10% CNFs were obtained via two-roll mill mixing of solid natural rubber with a master batch containing 20 wt% CNFs. The NR phase was cross-linked using sulphur vulcanization. The morphology studies showed that the dispersion of CNF in NR matrix was not optimal, and some aggregates were visible on the fracture surface. The tensile strength and modulus at 50% elongation increased for the nanocomposites with the addition of CNFs, accompanied by a moderate decrease in elongation at break. The storage modulus of the natural rubber significantly increased above its glass-rubber transition temperature upon nanofiber addition. The addition of CNFs also had a synergistic impact on the thermal stability of natural rubber. The susceptibility to organic solvents decreased significantly for the nanocomposites compared to crosslinked NR, which indicated restriction of polymer chain mobility in the vicinity of the nanosized CNFs in the NR matrix. PDF
Xia, K., Yang, R., Liu, D., Yang, F., Wang, B., and Li, L. (2012). "Degradation and stability of pulp treated in heterogeneous and homogeneous phases," BioRes. 7(2), 2169-2182.
This study aims to investigate the degradation and stability of pulp treated in heterogeneous and homogeneous phases. The results showed that the homogeneous system 1-Allyl-3-Hexylimidazolium chloride (AHIMCl) ionic liquid exhibited special dissolubility for pulp samples, but showed lower thermal stability than the heterogeneous treatments by 20 wt% NaOH or 2-ethanediamine (EDA) solution. Compared with the 20 wt% NaOH solution, the 20 wt% EDA solution and AHIMCl treatments had special decrystallizing ability, and the 20 wt% EDA solution had lower reductions in the mean degree of polymerization of pulp after the treatments for 72 h at 5 oC. X-ray diffractogram (XRD) analysis showed that after the AHIMCl and 20 wt% EDA solution treatments, the 002 crystal plane size of the treated pulp samples (<1 nm) became much lower than that of the raw pulp (5.09 nm). The diffracted intensity indicating 101 crystal planes nearly disappeared from the XRD curve of AHIMCl treated pulp samples. The X-ray photoelectron spectroscopy (XPS) analysis indicated that the significant reduction in C1s2 and O1s2 contents of the regenerated samples after the AHIMCl treatment implies that AHIMCl severely destroy the hydrogen bonds in crystalline and amorphous regions. PDF
Zhou, X., Chen, L., and Lin, Q. (2012). "Effects of chemical foaming agents on the physico-mechanical properties and rheological behavior of bamboo powder-polypropylene foamed composites," BioRes. 7(2), 2183-2198.
To make full use of bamboo resources in China and explore the foaming mechanism of bamboo powder-polypropylene (PP) foamed composites, a foamed composite of 54 wt% PP and 13 wt% HMSPP containing 33 wt% bamboo powder blends was prepared by injection moulding. Effects of chemical foaming agents (CFA) on the mechanical properties and rheological behavior of foamed composites were investigated. The mechanical measurements and ESEM test results indicated that the composite with 1% modified exothermic FA had smaller cell size and better cell distribution compared with endothermic FA. It also had better physico-mechanical properties, with a decrease of 14.2% in density and an increase of 16.8% to 40.2% in the specific tensile, bending, and notched impact strength compared with the non-foamed composite. The frequency sweep results indicated that all composites had a shear- thinning behavior, and both the modulus and complex viscosity of composite with 1% exothermic FA decreased compared with those of the non-foamed composite. The shear rate scans revealed that the non-Newtonian fluid index increased with the increase of exothermic FA content. The viscous activation energy of the modified composite with 1% exothermic FA was 46.41KJ·mol-1. This was an increase of 8.9% compared with that of the non-foamed analogue. PDF
Yue, F., Lan, W., Zhang, A., Liu, C., Sun, R., and Ye, J. (2012). "Dissolution of holocellulose in ionic liquid assisted with ball-milling pretreatment and ultrasound irradiation," BioRes. 7(2), 2199-2208.
One of the most promising technologies for lignocellulosic biomass utilization employs ionic liquids for the conversion of isolated components into fuels, pharmaceuticals, chemicals, and composites after fractionation of lignocellulose. However, the time required for dissolution of the whole cell wall has been excessive. To explore a possible dissolution and fractionation pathway of lignocelluloses, the dissolution of holocellulose isolated from bagasse was investigated in 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) assisted with ball-milling pretreatment and ultrasound irradiation. Ball milling pretreatment, ultrasonic irradiation assistance, and their combination were found to effectively improve the holocellulose dissolution in [C4mim]Cl. The effects of ultrasound power and irradiation duration on the dissolution time of ball-milled holocelluloses in [C4mim]Cl were studied. The regenerated holocelluloses were characterized with FT-IR, X-Ray, and CP/MAS 13C-NMR. It was found that there were no obvious changes of chemical structure after dissolution and regeneration of the holocellulose. The crystalline structure of cellulose was converted from cellulose I in native holocellulose to cellulose II in the regenerated holocellulose. The crystallinity decreased after the process of dissolution and regeneration assisted by ball-milling pretreatment and ultrasound irradiation. PDF
Cristóvão, L., Ekevad, M., and Grönlund, A. (2012). "Natural frequencies of roll-tensioned circular sawblades: Effects of roller loads, number of grooves, and groove positions," BioRes. 7(2), 2209-2219.
Roll-tensioning effects on natural frequencies in circular sawblades for woodcutting were investigated. Adequate knowledge of these effects will enable a more precise and repeatable tuning of natural frequencies, which will ease manufacturing and maintenance of sawblades. With natural frequencies tuned to not create resonance under running conditions, longer running times and more accurate cutting are made easier. The aim of this study was to find the optimum, or most suitable, tensioning parameters for a series of tested circular sawblades and also to draw general conclusions. The effects of the magnitude of the roller load, number of grooves, and groove positions were tested. The magnitude of the roller load was measured by using a universal load cell. The roll-tensioning effects were evaluated by measuring the shift in natural frequencies of several vibration modes. Finite element analysis was performed to model natural frequencies. The magnitude of the roller load, number of grooves, and groove positions all affected the natural frequencies. Natural frequencies obtained with the finite element method were in good agreement with the experimental test results. PDF
Thakur, V. V., Jain, R. K., and Mathur, R. M. (2012). "Studies on xylanase and laccase enzymatic prebleaching to reduce chlorine-based chemicals during CEH and ECF bleaching," BioRes. 7(2), 2220-2235.
The biobleaching efficiency of xylanase and laccase enzymes was studied on kraft pulps from wood and nonwood based raw materials employed in the Indian paper industry. Treatment of these pulps with xylanase enzyme could result in improved properties, showing 2.0% ISO gain in pulp brightness and/or reducing the demand of chlorine-based bleach chemicals by up to 15% with simultaneous reduction of 20 to 25% in AOX generation in bleach effluents. Further, mill-scale trial results revealed that enzymatic prebleaching can be successfully employed with xylanases to reach the same bleach boosting efficacy. Laccase bleaching was also studied on hardwood pulp at a pH around 8.0, where most of the pulp mills in India are operating, in contrast to earlier studies on laccase enzyme bleaching, which were conducted at acidic pHs, i.e. 4.0 to 5.0. In case of laccase bleaching, interesting results were found wherein a bleach-boosting effect was observed even at pH 8.0. Further studies carried out with HOBT as mediator in comparison to the commonly used and expensive ABTS laccase mediator system (LMS) resulted in improvement of the bleaching efficiency with reduction in demand of chlorine dioxide by more than 35%. Potential for further reduction was indicated by the brightness gain, when compared with a control using the DE(p)D bleach sequence. PDF
Chen, Y., Gao, J., Fan, Y., Tshabalala, M. A., and Stark, N. M. (2012). "Heat-induced chemical and color changes of extractive-free black locust (Robinia pseudoacacia) wood," BioRes. 7(2), 2236-2248.
To investigate chemical and color changes of the polymeric constituents of black locust (Robinia pseudoacacia) wood during heat treatment, extractive-free wood flour was conditioned to 30% initial moisture content (MC) and heated for 24 h at 120 °C in either an oxygen or nitrogen atmosphere. The color change was measured using the CIELAB color system. Chemical changes of the wood components were determined by means of solid state cross-polarization/magic angle spinning 13C-nuclear magnetic resonance (CPMAS-13C-NMR), Fourier transform infrared (FTIR), diffuse reflectance UV-Vis (DRUV) spectroscopy, and elemental (CHN) analysis. The results showed that lightness (L*) decreased, while chromaticity indexes (a* and b*) and chroma (C*) increased after heat treatment. There was greater color difference (ΔE*) in the samples heated in the presence of oxygen compared to nitrogen. CHN analysis showed an increase in hydrogen and oxygen and a decrease in carbon content. NMR spectra confirmed the cleavage of the β-O-4 structure in the lignin, resulting in a decrease in etherified lignin units and an increase in phenolic structures. DRUV and FTIR spectra confirmed the formation of extensive conjugated structures, such as unsaturated ketones and quinones due to the cleavage of the lignin units. Formation of quinones can be attributed to heat treatment in the presence of oxygen. PDF
Zhang, Y., Meng, Y., Wu, Y., Wang, S., Du, G., Jiang, H., and Zhou, Z. (2012). "Effect of enzyme treatment on the mechanical properties of wood cell walls by nanoindentation," BioRes. 7(2), 2249-2259.
The objective of this research was to study the changes in hardness and elastic modulus of wood cell walls treated with enzymes. Such changes greatly influence the properties of paper and wood composites. Two enzymes, hemicellulase and lipase, were selected for the treatment. Poplar samples (Populus euramevicana) were treated with hemicellulase, while samples of southern yellow pine (Pinus spp.) and Mongolia scotch pine (Pinus sylvestris L. var. mongolica Litv.) were treated with lipase. Mechanical properties of both treated samples were investigated by nanoindentation. The results showed some changes in the hardness and elastic modulus of the poplar cell wall treated by hemicellulase. Hardness and elastic modulus values of southern yellow pine and Mongolia scotch pine cell walls treated by lipase decreased with increasing amounts of the enzyme. PDF
Ma, P., Zhai, H., Law, K., and Daneault, C. (2012). "Influences of integrated TEMPO-mediated oxidation and recycling on the properties of TMP fibers," BioRes. 7(2), 2260-2271.
In order to improve the properties of thermomechanical pulp (TMP), the influences of the TEMPO (2,2,6,6-tetramethylpiperidyl-1-oxyl radical)-mediated oxidation on recycled TMP properties were investigated, and the impacts of recycling process on TEMPO-mediated oxidized TMP properties were studied as well. The results showed that TEMPO-mediated oxidation is an effective way to enhance the recycled TMP inter-fiber bonding dependent properties due to the introduction of carboxylic acid groups onto pulp, while the oxidation had some negative impacts on the tear index, zero span tensile index, and brightness. The oxidation-recycling (O-R) process had remarkable adverse impacts on TMP compared with the recycling-oxidation (R-O) process. The tensile, burst, tear strengths, as well as the zero-span tensile strength dropped sharply when oxidized TMP was recycled, and the physical strength properties decreased with the increasing recycling times. The opacity was improved after the O-R treatment, although the O-R treatment had an adverse impact on the pulp brightness. PDF
Min, D., Jameel, H., Chiang, V., and Chang, H.-M. (2012). "Effect of lignin on enzymatic saccharification of hardwood after green liquor and sulfuric acid pretreatments," BioRes. 7(2), 2272-2283.
Red maple, sweet gum, trembling aspen, red alder, and Eucalyptus globulus samples were pretreated with dilute sulfuric acid and green liquor before enzymatic saccharification. Substrates showed different levels of delignification and sugar recovery, depending on the applied pretreatments and the syringaldehyde/vanillin ratio (S/V). Three major conclusions were drawn in this research. First, lignin is the greatest contributor to recalcitrance of hardwood to enzymatic saccharification. Second, a high S/V ratio is a useful indicator of high delignification during a pretreatment process. Third, green liquor pretreatment is a promising pretreatment method because of a high delignification degree and sugar recovery. In addition, xylan also contributes to the recalcitrance of hardwoods toward enzymatic saccharification. PDF
Karlsson, O., Yang, Q., Sehlstedt-Persson, M., and Morén, T. (2012). "Heat treatments of high temperature dried Norway spruce boards: Saccharides and furfurals in sapwood surfaces," BioRes. 7(2), 2284-2299.
Carbohydrates that migrate to wood surfaces in sapwood during drying might influence properties such as mould susceptibility and colour. Sugars on the surface of Norway spruce boards during various heat treatments were studied. Samples (350mmx125mmx25mm) were double-stacked, facing sapwood-side outwards, and dried at 110oC to a target moisture content (MC) of 40%. Dried sub-samples (80 mm x 125 mm x 25 mm) were stacked in a similar way and further heated at 110oC and at 130oC for 12, 24, and 36 hours, respectively. Glucose, fructose, and sucrose as well as 5-hydroxymethylfurfural (HMF) and furfural in the sapwood surface layer of treated wood were analysed using HPLC (RI- and UV-detectors). Carbohydrates degraded to a lower extent at 110oC than at 130oC. Furfural and to a larger extent HMF increased with treatment period and temperature. Heat treatment led to a decrease in lightness and hue of the sapwood surface of sub-samples, while chroma increased somewhat. Furthermore, considerably faster degradation (within a few minutes) of the carbohydrates on the surface of the dried spruce boards was observed when single sub-samples were conductively hot pressed at 200oC. Treatment period and initial MC influenced the presence of the carbohydrates in wood surface as well as colour change (DEab) of the hot pressed sub-samples. PDF
De Souza, J. V. T. M., Diniz, K. M., Massocatto, C. L., Tarley, C. R. T., Caetano, J., and Dragunski, D. C. (2012). "Removal of Pb(II) from aqueous solution with orange sub-products chemically modified as biosorbent," BioRes. 7(2), 2300-2318.
The effects of chemical modification of orange peel, bagasse, and a mixture of peel and bagasse for lead ion removal from aqueous medium were evaluated. The chemical modification of biomass was carried out with sodium hydroxide and citric acid to introduce carboxylate groups on the surface of the biomass. Infrared spectra confirmed the presence of carboxylate groups at 1735 cm-1. Adsorption isotherms performed by static adsorption experiments fitted very well to the linear Langmuir and Freundlich models. The experiments were carried out at pH 5 during 500 min of shaking time. Orange modified peel (O-MP) presented the highest adsorption capacity (84.5 mg g-1), notably higher than other biosorbents described in the literature. The kinetic studies showed that the process obeyed a pseudo-second-order rate expression, thus indicating a strong interaction between the biosorbent and adsorbate. It was found that the chemical modifications of sorbents promoted an adsorption energetically more spontaneous, as indicated by negative values of Gibbs free energy. On the other hand, desorption studies showed low leaching of lead ions from the biosorbent, thus confirming the strong interaction of lead ions and the biosorbent. The satisfactory maximum adsorption capacity obtained and negligible cost of biosorbent makes the sub-products of orange a reliable natural material for the removal of lead ions from aqueous effluents. PDF
Fu, G., He, A., Jin, Y., Cheng, Q., and Song, J. (2012). "Fabrication of hollow silica nanorods using nanocrystalline cellulose as templates," BioRes. 7(2), 2319-2329.
A simple approach to fabricate hollow silica nanorods is reported, using nanocrystalline cellulose (NCC) as templates. Uniform NCC with the length of ca. 100 nm and a diameter of ca. 10 nm were prepared by hydrolysis of microcrystalline cellulose (MCC) in strong sulfuric acid condition. NCC was used as a template to prepare a core-shell composite of silica and NCC. The sol-gel reaction of tetraethyl orthosilicate (TEOS) was employed to coat NCC with a nano thickness of silica in the presence of ammonia. Finally, hollow silica nanorods were obtained by calcination of the composite at 600°C to remove the organic cellulose template completely. The obtained hollow silica nanorods were found to have uniform size and shape: with a length of ca. 100 nm, an inner diameter close to the original diameter of NCC, and a thickness of around 10 to 15 nm. These results suggest that NCC is an excellent template for manufacturing nano hollow materials with uniform shape and size. PDF
Li, F., Yang, S., Zhao, L., Li, Q., and Pei, J. (2012). "Synonymous condon usage bias and overexpression of a synthetic xynB gene from Aspergillus niger NL-1 in Pichia pastoris," BioRes. 7(2), 2330-2343.
To further improve the expression level of recombinant xylanase in Pichia pastoris, the xynB gene, encoding the mature peptide from Aspergillus niger NL-1, was designed and synthesized based on the synonymous condon bias of P. pastoris and optimized G+C content. 155 nucleotides were changed, and the GC content decreased from 57.7% to 43.6%. The synthetic xynB was inserted into the pPICZaA and then integrated into P. pastoris GS115. The activity of the recombinant xylanase reached 1414.7 U/mL, induced with 0.8% methanol after 14-day cultivation at a temperature of 28oC in shake flasks, which was 267% higher than that of the native gene. Furthermore, the maximum xylanase activity of 20424.2 U/mL was obtained by high-density fermentation in a 5-L fermenter, which was the highest xylanase expression in P. pastoris yet reported. The recombinant xylanase had its optimal activity at a pH of 5.0 and temperature of 50oC. The recombinant xylanase was stable over a pH range of 4.5 to 8.0. Thus, this report provides an industrial means to produce the recombinant xylanase in P. pastoris. PDF
Jawaid, M., Abdul Khalil, H. P. S., Hassan, A., and Abdallah, E. (2012). "Bi-layer hybrid biocomposites: Chemical resistant and physical properties," BioRes. 7(2), 2344-2355.
Bi-layer hybrid biocomposites were fabricated by hand lay-up technique by reinforcing oil palm empty fruit bunch (EFB) and jute fibre mats with epoxy matrix. Hybrid composites were prepared by varying the relative weight fraction of the two fibres. The physical (void content, density, dimensional stability), and chemical resistant properties of hybrid composites were evaluated. When the jute fibre loading increased in hybrid composites, physical and chemical resistant properties of hybrid composites were enhanced. Void content of hybrid composites decreased with an increase in jute fibre loading because jute fibres showed better fibre/matrix interface bonding, which leads to a reduction in voids. The density of hybrid composite increased as the quantity of jute fibre loading increased. The hybridization of the jute fibres with EFB composite improved the dimensional stability of the hybrid composites. The performance of hybrid composites towards chemical reagents improved with an increase in jute fibre loading as compared to the EFB composite. The combination of oil palm EFB/jute fibres with epoxy matrix produced hybrid biocomposites material that is competitive to synthetic composites. PDF
Gao, Y., Qin, M., Zhang, F., Li, Z., and Li, L. (2012). "GC-MS analysis of sticky contaminants in a deinking pulping line," BioRes. 7(2), 2356-2365.
Pulps were sampled from three major points of a deinking pulping line and classified as fibers fraction, fines fraction, and aqueous phase, respectively, then extracted with tetrahydrofuran (THF) or methyl tert-butyl ether (MTBE). Sticky contaminants in the extractives were examined by GC-MS analysis. The results showed that the contaminants can be grouped as adhesive substances, wood extractives, lignin-derivatives, and other organic acids, of which the adhesive substances were accounted as the major component. Contents of sticky components in each group and their removal were further evaluated according to the related unit operation. Adhesives remaining in fibers and fines fractions were removed by the post-flotation. Wood extractives and degraded residual lignins were also released to some extent from pulp fibers during heat-dispersing, and then removed during the post-flotation. PDF
da Penha, M. P., da Rocha-Leão, M. H. M., and Leite, S. G. F. (2012). "Sugarcane bagasse as support for the production of coconut aroma by solid state fermentation (SSF)," BioRes. 7(2), 2366-2375.
Brazil is one of the major producers of sugarcane (Saccharum officinarum) in the world and consequently produces large quantities of waste such as sugarcane bagasse, which can be used as inert support for the production of aroma compounds by SSF. The aim of this study was to evaluate the centesimal composition and particle size distribution of sugar cane bagasse, as well as its applicability as support for the production of 6-pentyl-α-pyrone by SSF. Analyses were performed in triplicate to evaluate the levels of carbohydrates, proteins, lipids, and moisture in the waste. Also evaluated were the particle size distribution and morphology structure of the sugarcane bagasse. The aroma compound produced shows that the studied waste can be used for 6PP production by Trichoderma harzianum IOC 4042 by SSF process. By kinetic production of aroma it is concluded that the seventh day of fermentation yielded the largest production of the aroma compound, as published for other studies. PDF
Zasadowski, D., Hedenström, E., Edlund, H., and Norgren, M. (2012). "Removal of lipophilic extractives and manganese ions from spruce TMP waters in a customized flotation cell," BioRes. 7(2), 2376-2392.
The influence of a chelating surfactant, different foaming agents, cationic polyelectrolytes, pH value, and temperature on the purification efficiency of process waters from a mechanical pulp mill has been studied by flotation in a 1 L customized unit. Turbidity measurements and gas chromatography (GC) were carried out to determine the removal and characteristics of dissolved and colloidal substances (DisCo). The manganese ion content in the process waters before flotation and the metal chelate removal capacity by flotation were determined by Inductively Coupled Plasma (ICP) and Atomic Absorption Spectrometry (AAS) measurements. It was found that a 99% removal of complex bound manganese ions and a 94% decrease in turbidity of the TMP water produced at the laboratory can be achieved in a single-stage flotation with a chelating surfactant and a foaming agent. Furthermore, a 91% decrease in turbidity, the removal of up to 96% of resin and fatty acids, and 93% of triglycerides from TMP water can be obtained after application of a foaming agent. PDF
Feraydoni, V., and Hosseinihashemi, S. K. (2012). "Effect of walnut heartwood extractives, acid copper chromate, and boric acid on white-rot decay resistance of treated beech sapwood," BioRes. 7(2), 2393-2402.
This study evaluates the individual and interaction effects of wood extractives, acid copper chromate (ACC), and boric acid (B) on the resistance to fungus of treated wood species. Walnut (Juglans regia L.) heartwood extractives were extracted with hot water, methanol, and ethanol solvents. Test specimens were prepared from beech sapwood (Fagus orientalis) to meet BS 838 (1961) requirements, then exposed to white-rot fungus, Trametes versicolor, for 14 weeks under laboratory conditions. Extractives of walnut heartwood contributed to increased resistance against fungus attack in the presence of B preservative only. The lowest weight loss (0.12%) occurred in the samples treated with 3.5% hot water extract and 1% boric acid, and the highest weight loss occurred in the control samples (23.7%). Results indicated that there was significant difference between the weight loss and actual retention for all treatments, but there was not any significant difference between the weight loss of treatments containing B preservative. The weight loss of samples treated with hot water extract (18.32%) was less than samples treated with methanol and ethanol extracts (21.5% and 23.1%, respectively). There was significant difference between the individual and interaction effects of wood extractives on the resistance to fungus of treated wood species. An emulsified mixture of B and walnut heartwood extractives controlled decay fungus on beech wood better than the mixture of ACC and walnut heartwood extractives, but ACC alone controlled decay fungus on beech wood better than the emulsified mixture of ACC and walnut heartwood extractives. PDF
Chen, Y.-L., Lin, C.-Y., Wu, T.-L., Chung, M.-J., Chen, T.-Y., Yang, T.-H., Chen, H.-C., and Wu, J.-H. (2012). "Evaluation and application of the invasive weed Mikania micrantha as an alternative reinforcement in recycled high density polyethylene," BioRes. 7(2), 2403-2417.
In this study Mikania micrantha particle (MP) and fiber (MF) were added to recycled high density polyethylene (rHDPE) for producing natural fiber (or particle) reinforced plastic composites (NFRPC) by the flat-platen pressing process. The results showed that the flexural strength and stiffness of NFRPC were significantly improved through incorporating M. micrantha particle and fiber. Higher aspect ratio of reinforcement displayed stronger mechanical properties. The vertical density profile in composites significantly influenced the mechanical properties of NFRPC. A conventional V-shaped profile and a uniform vertical density profile (homo-profile) were observed in MP and MF based NFRPC, respectively. Additionally, with increasing lignocellulose content, a more uniform vertical density profile and higher wood screw holding strength were observed. These results indicate M. micrantha particle and fiber are excellent reinforcements for NFRPC applications. PDF
Chang, S., Quignard, F., Di Renzo, F., and Clair, B. (2012). "Solvent polarity and internal stresses control the swelling behavior of green wood during dehydration in organic solution," BioRes. 7(2), 2418-2430.
The dimensional variations of green wood samples induced by organic solvents have been studied. The solvents used (ethanol, isopropanol, acetone, and acetonitrile) covered a wide range of polarity and were studied pure and in aqueous solutions over a wide range of concentrations. Samples of normal and tension wood of poplar were used in order to minimize the effect of hydrophobic extractives on the wood-solvent interactions. The evolution of wood volume and of tangential strain with the concentration of the organic solvents shows a behavior similar to gels, with a significant swelling for solutions of intermediate polarity. The similarity of volume obtained in water and less polar pure organic solvents strikingly contrasted the different effects of water and organic solvents on dry wood. Low-polarity solvents were extremely effective in the stress release of tension wood, as indicated by the pattern of longitudinal shrinkage. Solvent exchange does not affect the mesoporous structure of the cell walls of tension wood and is a promising way to reduce internal stress in wood products. PDF
Xu, P., Bao, J., Gao, J., Zhou, T., and Wang, Y. (2012). "Optimization of extraction of phenolic antioxidants from tea (Camellia sinensis L.) fruit peel biomass using response surface methodology," BioRes. 7(2), 2431-2443.
Tea (Camellia sinensis L.) fruit peel, the main byproduct during the manufacture of tea seed oil, was used as raw material for the recovery of phenolic antioxidants. The effect of ethanol concentration, extraction time, and extraction temperature on total phenolic content (TPC) and ferric-reducing antioxidant power (FRAP) of the extracts from tea fruit peel was investigated. The maximum predicted TPC (47.5 mg GAE/g dry peel) was obtained under the optimum recovery conditions (43% ethanol, 60°C, and 33 min) given by using response surface methodology (RSM). A high correlation (R2 = 0.929, p < 0.01) between TPC and FRAP value was identified by linear regression analysis. Furthermore, gallocatechin (GC) and epigallocatechin (EGC) were found to be the major individual catechins in the extracts from tea fruit peel. Ethanol/aqueous extraction has been presented as an effective method for the recovery of phenolic antioxidants from tea fruit peel. PDF
Huang, S., Wang, B. J., Lu, J., Dai, C., Lei, Y., and Sun, X. (2012). "Characterizing Changbai larch through veneering. Part 1: Effect of stand density," BioRes. 7(2), 2444-2460.
Changbai larch (Larix olgensis Henry) is one of the main plantation species in the northern part of China, but so far its utilization has been limited to solid wood, pulping, and paper products. As part of a national initiative, the objective of this work was to develop a good understanding concerning how stand management practices affect larch wood and veneer properties. To cope with the variation of initial and final stand density, the term "relative thinning intensity (RTI)" was introduced to describe the effect of stand thinning on the resulting wood and veneer properties. Nine representative sample trees each from four stands were harvested, then trimmed and bucked. Six 1.25 m long bolts along the entire tree stem were systematically cut to peel 2.6 mm thick veneers. Clear wood specimens were also sawn from matched bolts for mechanical testing for the purpose of comparison and validation. The correlation between the main tree variables and properties of clear wood and veneer was analyzed, and the influence of RTI on key wood and veneer properties was examined and compared. A good correlation was found in density and modulus of elasticity (MOE) between larch clear wood and veneer, giving an R2 of 0.75 and 0.71, respectively. This indicates that veneering can be potentially used to characterize this larch species. The stand with the lowest RTI had the shortest rotation but yielded the best properties of both clear wood and veneer, which highlights the importance of stand management in terms of thinning. PDF
Stirling, R., and Morris, P. I. (2012). "Treatments to minimize extractives stain in Western red cedar," BioRes. 7(2), 2461-2468.
Under certain conditions involving uneven exposure to weather, stains related to the extractives can reduce the aesthetic appeal of western red cedar in exterior applications such as fence boards, siding, and sidewall shingles. Selected chemical treatments were evaluated for their ability to inhibit the formation of extractives stain. DDACarbonate, alkyl amine oxide, and combinations thereof delayed extractives stain formation in an accelerated field test, with higher loadings having greater effect. PDF
Wang, W., Zhuang, X., Yuan, Z., Yu, Q., Qi, W., Wang, Q., and Tan, X. (2012). "Effect of structural changes on enzymatic hydrolysis of eucalyptus, sweet sorghum bagasse, and sugarcane bagasse after liquid hot water pretreatment," BioRes. 7(2), 2469-2482.
A woody (eucalyptus (Eu)) and two herbaceous materials (sweet sorghum bagasse (SSB) and sugarcane bagasse (SCB)) were used to evaluate the effect of liquid hot water (LHW) pretreatment on enzymatic hydrolysis of various lignocelluloses. The results showed that enzymatic hydrolysis efficiency of pretreated materials was SCB>SSB>Eu at 5% solids loading, while SSB>SCB>Eu was at 10% and 20% solids loadings. This indicated the enzymatic hydrolysis efficiency of SCB could be influenced by solids concentration. The differences in surface morphology, crystalline structure, and functional groups of pretreated samples were also examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. SEM photographs and crystallinity indexes (CrI) showed that the structural compactness was Eu>SSB>SCB for both of untreated and treated materials. FTIR spectra showed that the conspicuousness of physicochemical changes was SCB>SSB>Eu. The differences in enzymatic hydrolysis efficiency of pretreated materials can be ascribed mainly to the structural differences. PDF
Frybort, S., Mauritz, R., Teischinger, A., and Müller, U. (2012). "Investigation of the mechanical interactions at the interface of wood-cement composites by means of electronic speckle pattern interferometry," BioRes. 7(2), 2483-2495.
This study investigates the bonding behaviour of Norway spruce wood strands to a surrounding cement matrix. Effects of wood swelling and shrinking during cement curing were studied by using strands of various thicknesses. The deformation of the spruce wood strands and the surrounding cement matrix, as well as the interface between the wood and the cement were examined using Electronic Laser Speckle Interferometry (ESPI) while applying a pull-out load. Sample deformation was transformed to shear strain maps, showing which side of the strand was tightly bonded to the cement matrix. The analysis of the strain maps proved that all strands were tightly bonded to the cement matrix on only one side. No shear deformation was observed on the loosely bonded side, meaning that there was no adhesion on that side between the wood strand and the cement matrix. Manufacturing of strands results in different surface characteristics and surface roughness. Bringing together the ESPI results with the roughness measurements, it was shown that only the comparably rougher surface adheres to the cement matrix. In a cement bonded composite (CBC) made of lignocellulosics to a greater or lesser extent, only half of the contact area is therefore able to transfer load. PDF
Ncube, E. (2012). "Predicting thickness swelling of hot-pressed wood strands," BioRes. 7(2), 2496-2505.
Strand board can be manufactured from sawmill residues, branches, and crown wood left in the forest. The thickness swelling of these residues is quite different from that of mature wood and can have a negative effect on the physical and strength properties of strand board. A mixture of these materials and pressing conditions can be optimized by assessing thickness swelling of wood strands after pressing. Individual wood strands conditioned to 12% moisture content were hot-pressed at 105 °C to 50% of their original thickness and conditioned at 20 °C and 33%, 100%, and 0% relative humidity for 72 hours to determine their thickness swelling. A mechanical model consisting of springs and dashpots was superimposed on a stress relaxation curve to determine strain components with a view to predict thickness swelling. The data were interpreted by analysis of variance in conjunction with Fisher's protected least significant difference method. The results showed a good agreement between measured and predicted thickness swelling of both juvenile and mature wood. PDF
Johansson, C., Bras, J., Mondragon, I., Nechita, P., Plackett, D., Šimon, P., Svetec, D. G., Virtanen, S., Baschetti, M. G., Breen, C., Clegg, F., and Aucejo, S. (2012). "Renewable fibers and bio-based materials for packaging applications - A review of recent developments," BioRes. 7(2), 2506-2552.
This review describes the state-of-the-art of material derived from the forest sector with respect to its potential for use in the packaging industry. Some innovative approaches are highlighted. The aim is to cover recent developments and key challenges for successful introduction of renewable materials in the packaging market. The covered subjects are renewable fibers and bio-based polymers for use in bioplastics or as coatings for paper-based packaging materials. Current market sizes and forecasts are also presented. Competitive mechanical, thermal, and barrier properties along with material availability and ease of processing are identified as fundamental issues for sustainable utilization of renewable materials. PDF
Popil, R. E. (2012). "Overview of recent studies at IPST on corrugated board edge compression strength: Testing methods and effects of interflute buckling," BioRes. 7(2), 2553-2581.
Several recent series of investigations were conducted on corrugated board performance in the areas of: loaded container endurance in cyclic humidity, predictive models for edge compression strength (ECT), effects of lightweight facings, measurement of transverse shear rigidity, effects of adhesive level, and out-of-plane crushing on ECT. The course of this program prompted exploration and review of several aspects of ECT testing methods: specimen height, test duration, and fixture-clamping effects. In this review, ECT values are shown to be influenced by the combination of the selected testing technique with the specific structural and strength characteristics of the board being tested. The effect of specimen height on selected single wall C-, E-, F-, and N-flute boards is measured and rationalized using a simplified beam-theory approach. Apparent loss of ECT in a C-flute crushed board is explored to determine whether mitigation is possible by selection or modification of testing method. Investigations of platen speed effects on C-flute substantiate previous work. Lightweight facings on A- and C-flute corrugated boards are observed to display localized buckling, which affects the ECT value. An analytical model that combines the measured bending stiffness of the facings and the compression strengths of the fluting and facings provides an improved predictive accuracy and is applied to a series of laboratory and commercial corrugated boards. PDF
Shi, H., Liu, H., Ni, Y., Yuan, Z., Zou, X., and Zhou, Y. (2012). "Review: Use of optical brightening agents (OBAs) in the production of paper containing high-yield pulps," BioRes. 7(2), 2582-2591.
The efficiency of optical brightening agents (OBAs), also known as fluorescent whitening agents (FWAs), has long been of interest in the production of uncoated fine paper, particularly in uncoated fine paper grades containing high-yield pulp (HYP). The increasing levels of whiteness and also the increasing HYP substitution in fine papers has made OBA efficiency an important issue. This paper summarizes recent research findings in understanding and enhancing OBA efficiency in fine papers containing HYP, with focus on the main factors affecting OBA efficiency in both wet end and size press application. These factors include the base sheet brightness and whiteness of the pulp, UV competitors, OBA retention, quenching effects, and OBA migration at the size press. Some new technologies to improve OBA efficiency are discussed. PDF
Hubbe, M. A., Beck, K. R., O'Neal, W. G., and Sharma, Y. C. (2012). "Cellulosic substrates for removal of pollutants from aqueous systems: A review. 2. Dyes," BioRes. 7(2), 2592-2687.
Dyes used in the coloration of textiles, paper, and other products are highly visible, sometimes toxic, and sometimes resistant to biological breakdown; thus it is important to minimize their release into aqueous environments. This review article considers how biosorption of dyes onto cellulose-related materials has the potential to address such concerns. Numerous publications have described how a variety of biomass-derived substrates can be used to absorb different classes of dyestuff from dilute aqueous solutions. Progress also has been achieved in understanding the thermodynamics, kinetics, and chemical factors that control the uptake of dyes. Important questions remain to be more fully investigated, such as those involving the full life-cycle of cellulosic substrates that are used for the collection of dyes. Also, more work needs to be done in order to establish whether biosorption should be implemented as a separate unit operation, or whether it ought to be integrated with other water treatment technologies, including the enzymatic breakdown of chromophores. PDF
Sulaiman, O., Salim, N., Nordin, N. A., Hashim, R., Ibrahim, M., and Sato, M. (2012). "The potential of oil palm trunk biomass as an alternative source for compressed wood," BioRes. 7(2), 2688-2706.
Compressed wood, which is formed by a process that increases the wood's density, aims to improve its strength and dimensional stability. Compressed wood can be used in building and construction, especially for construction of walls and flooring. Currently, supplies of wood are becoming limited, and the oil palm tree has become one of the largest plantation species in Malaysia. Oil palm trunk could be an appropriate choice for an alternative source for compressed wood. This paper aims to review the current status of oil palm biomass, including the availability of this tree, in order to illustrate the potential of oil palm biomass as an alternative source for compressed wood. Up to the present there has been insufficient information regarding the manufacturing conditions and properties of compressed wood from oil palm trunk. This paper will cover the background of compressed wood and the possibilities of producing compressed wood using oil palm trunk as a raw material. PDF