distribution of its particles. The viscosity of filled systems generally increases with increasing filler fraction. This can be partially ameliorated via broad particle size distributions via the Farris effect. An additional factor is the stress transfer at the filler-polymer interface. The interfacial adhesion can be substantially enhanced via a coupling agent that adheres well to both the polymer and the filler particles. The type and amount of surface treatment on the filler are thus additional parameters affecting the rheological and material properties of filled polymeric systems. It is important to take into consideration wall slip when performing the rheological characterization of highly filled materials, as there can be a large difference between the actual strain and the measured strain. Rheologist A rheologist is an interdisciplinary scientist or engineer who studies the flow of complex liquids or the deformation of soft solids. It is not a primary degree subject; there is no qualification of rheologist as such. Most rheologists have a qualification in mathematics, the physical sciences (e.g. chemistry, physics, geology, biology), engineering (e.g. mechanical, chemical, materials science, plastics engineering and engineering or civil engineering), medicine, or certain technologies, notably materials or food. Typically, a small amount of rheology may be studied when obtaining a degree, but a person working in rheology will extend this knowledge during postgraduate research or by attending short courses and by joining a professional association. See also Bingham plastic Die swell Fluid dynamics Glass transition Liquid List of rheologists Microrheology Rheological weldability for thermoplastics Rheopectic Solid Transport phenomena Interfacial rheology References External links "The Origins of Rheology: A short historical excursion" by Deepak Doraiswamy, DuPont iTechnologies RHEOTEST Medingen GmbH – Short history and collection of rheological instruments from the time of Fritz Höppler - On the Rheology of Cats Societies American Society of Rheology Australian Society of Rheology British Society of Rheology European Society of Rheology French Society of Rheology Nordic Rheology Society Romanian Society of Rheology Korean Society of Rheology Journals Applied Rheology Journal of Non-Newtonian Fluid Mechanics Journal of Rheology Rheologica Acta Tribology