Polymer melts are highly viscous due to their long molecular chain structure. Polymer viscosity can be thought of as the thickness of a fluid, or how much it resists flow. This is expressed as the ratio of shear stress (force per unit area) to the shear rate (rate change of shear strain). The rheological behavior of most polymeric materials is very complex, and although measurement can be done, it is typically done under very complicated conditions- at high pressure and high temperature. This webinar reviews melt and intrinsic definitions, and online and offline polymer viscosity measurement techniques.
