(4ak) A Full-Chain Stochastic Tube Model for Entangled Polymeric Liquids: Improvement for Extended Applications

A full-chain stochastic tube model developed by Xu et al. [J. Rheology (2006) 50:477-494] was modified to simulate entangled melts and solutions of linear polymers at high shear rates. This model, which has only one adjustable parameter equivalent to the Rouse time, successfully describes shear and normal stress data at low to moderate rates, but the model deviates systematically from data at high rates. The algorithm for re-entanglement has been modified to reduce the deviation in the calculated viscosity at high rates. The discussion focuses on the structural changes in terms of the constraint renewal mechanism, the effect of a non-uniform drag coefficient of chains, and the entanglement density.