“Volume preserving” rheological models for polymer melts and solutions using the GENERIC formalism

A constrained rheological model for polymer solutions and melts is developed using the GENERIC formulation. The constraint, det c=constant, where c is a conformation tensor, is introduced in the general formulation using a modified mobility tensor, Λ1, and a Helmholtz free-energy function expressed in terms of the scaled invariants of the conformation tensor. The predictions of this family of “volume-preserving” models are illustrated for a modified Hookean energy function and several expressions of the modified mobility tensor. The predictions are compared to experimental data taken from the literature for polymer melts and polymer solutions. The sensitivity of the predictions to model parameters (a maximum of four for this particular case) shows that in steady and transient shear flows, it is possible to cover a wide range of rheological behaviors generally observed for polymer melts and solutions. Comparison with experimental results for polymer melts and solutions shows that the model predicts very we...