Strong flows of polymeric liquids: Part 1. Rheological behaviour

Abstract

This work deals with constructing the rheological constitutive equations (RCEs) for concentrated polymer solutions and melts within the framework of their micromechanical models. A brief review of the state of the problem is given in the introduction. In Section 2, the separation of physical processes, proceeding from the physical model of the polymeric liquids' inner structure is used to construct RCEs suitable for describing the behaviour of concentrated systems at high rates of strain (i.e. in strong flows). These RCEs are applied in Section 3 to describe experiments with shear, uniaxial elongation and relaxation of stresses after cessation of straining in concentrated systems. Section 2 shows that, in the case of the short strong uniaxial elongation of concentration polymeric systems which is important for polymer processing, the micromechanical RCEs constructed in the paper are reduced to the phenomenological upper-convected Maxwell RCE. In the case of weak straining, the RCEs constructed in the paper reduce to the Doi-Edwards constitutive equation.