A CONSTITUTIVE THEORY FOR POLYOLEFINS IN LARGE-AMPLITUDE OSCILLATORY SHEAR

A versatile transient network theory has been used as a framework for the interpretation of large amplitude oscillatory behavior of polyolef in melts in terms of their entanglement kinetics. The model reasonably describes all previously published measurements of the large amplitud e oscillatory shear behavior on melts. Seven polyolefins are examined, three new materials and four previously studied. A qualitative differ ence in the nonlinear behavior in large amplitude oscillatory shear ha s been identified between the polyethylenes examined and the two other polyolefins, polystyrene and polyisobutylene.