Towards realistic rheological models for polymer melt processing

Greatly needed improvements to rheological models of polymer fluids can best be made by understanding and modifying a model on the molecular level, where the physics governing real fluids are created. For this purpose, stochastic simulations are an indispensible tool. The usefulness of stochastic simulations for kinetic theory models are well-known. In this paper, we show that the class of Rivlin-Sawyers, or K-BKZ, integral models is also subject to a molecular interpretation and can be simulated using stochastic techniques. We also illustrate how an existing molecular model can be modified, resulting in better predictions of viscoelastic behavior. For this we formulate a stochastic simulation of a reptation model modified to account for double reptation and tube-length fluctuations.