Université Laval

Canada

Keywords: polymer blends, volume preserving models, shear flows

Using a modified mobility tensor, two conformation tensors, c1 and c2, are introduced to describe the microstructure of dissimilar chains for a binary miscible polymer blend in the melt state. Based on the GENERIC formulism, the Helmholtz free-energy functions for 1-1, 2-2 and 1-2 types of pair interaction contacts in terms of the scaled invariants of the two conformation tensors and further using the constraint det c=1, a family of “volume preserving” rheological models are developed to predict the shear flow of polymer blends. A large rheological window, e.g. shear rate varying from 10-3 to 103 s-1, can be generally observed by using well adjusted model parameters. The model predictions for the steady shear viscosity and first normal stress coefficient of PS/PPO blends are in good agreement with experimental results. The predictions for shear stress in relaxation are also studied.