Structural Viscosity and Structural Elasticity of Polymer Melts

Abstract

A new structural approach to describing the non-Newtonian flow of polymer melts is suggested. The structural rheological model is the generalization of the known Casson and Cross rheological models. The use of equations of the structural rheological model allows description of rheological curves of steady-state shear flow and of curves of dynamic moduli without using the power law and the mechanical spring and damper models. The applicability of the model to melts of polymers of different structures and the occurrence of different flow modes were demonstrated. Methods for constructing the generalized flow curve in reduced coordinates and obtaining the temperature–time superposition were suggested. The coefficients of the rheological equations depend on the temperature and molecular mass of the polymer.