Linear macroscopic properties of polymeric liquids and melts. A new approach

Abstract

We present a new approach to the linear macroscopic behaviour of polymeric liquids and melts in terms of the macroscopic variables : velocity field, density, entropy density and strain field and we discuss how the classical Maxwell model emerges as a limiting special case. The novel approach used here, which considers the strain field as an additional macroscopic variable that relaxes on the timescale of the Maxwell time, allows to incorporate additional variables such as the macroscopic polarization or the concentration in mixtures easily. We point out a number of new cross-couplings not given before in connection with the Maxwell model and we outline four experiments to test some of the suggestions made. We predict for example that transverse acoustic phonons can be excited in a transient network with a frequency larger than the Maxwell frequency of the polymer melt or solution studied