Journal of Chemical Physics, Vol.101, No.6, 5293-5304, 1994
Anisotropic Friction and Excluded-Volume Effects in Freely Jointed Bead-Rod Polymer-Chain Models
We have studied the kinematics and theological properties of undiluted polymers by modeling the fluids as a collection of interacting Kramers freely jointed bead-rod chains with anisotropic friction using Brownian dynamics simulations. The anisotropic friction depends on the instantaneous configuration of the system. The resulting stochastic differential equations have multiplicative noise. The correlation of the "Langevin" Brownian forces appearing in these equations turns out to be anisotropic as well. The excluded volume effect, often ignored in kinetic theory, plays an important role in the behavior of short polymer chains. The chain kinematics may be distorted in its absence. In this work, we also discuss the effects of two types of excluded volume (EV) forces (hard-sphere and soft-repulsive forces) on theological properties of concentrated polymer solutions.
Keywords:ENCAPSULATED DUMBBELL MODEL;RHEOLOGICAL PROPERTIES;KINETIC-THEORY;CONSTITUTIVE EQUATION;DYNAMICS;MELTS;SYSTEMS;MOTION;SHEAR;FLOWS