Separation of elastic and viscous effects in polymer melt extrusion

Viscosity and elasticity of polymer melts respond differently to changes in extrusion conditions and to thermal and shear history of the polymer sample. Some reasons for this difference in behavior are summarized in this communication, which also presents new data on the topic. The results are rationalized on the basis of chain flexibility and interaction concepts, permitting the prediction of certain experimentally verifiable aspects of polymer melt rheology.