Shear banding in simulations of polymer melts

Results from numerical simulations of polymers under shear flow are compared with predictions for shear banding based on a model coupling Rolie-Poly-like tube dynamics to the entanglement dynamics mediated by convected constraint release (CCR). CCR is controlled by a parameter β, whose dependence on the bending stiffness kθ is calculated from the simulations. The model predicts shear banding for polymers whose equilibrium entanglement number Z exceeds a critical value Zc that depends on β. The simulations are in semiquantitative agreement with the model, with deviations that are attributed to approximations inherent in the model, and the inadequacy of tube models to describe partially disentangled liquids in strong flow. These results may help determine which physical polymers could undergo shear banding.