Volume 110, Issue 14, 08 April 1999
Index of content:
110(1999); http://dx.doi.org/10.1063/1.478565View Description Hide Description
The Poissonian character of the reversible part of nonequilibrium dynamics is exploited here in order to determine a dynamically consistent expression for a reptationmodel without the independent alignment assumption. It is shown that the previously proposed form by Doi and Edwards for such a model is compatible with the GENERIC formalism of nonequilibrium thermodynamics [Phys. Rev. E 56, 6620 (1997); 56, 6633 (1997)] only after two changes are made: (a) the production term in the evolution equation involves an average of the orientation dyadic uu over the entire internal phase space, and (b) the extra stress tensor involves an additional term, qualitatively different from the one representing the original Doi–Edwards expression. The predictions of the new model for the stress after double shear strain with flow reversal are shown to be realistic, demonstrating irreversibility effects, in contrast to the model with the independent alignment approximation.
110(1999); http://dx.doi.org/10.1063/1.478566View Description Hide Description
We extend the liquid-state theory of polymer fluids to include anisotropy as a key feature. The formalism is quite general. In determining the structure of anisotropicpolymer fluids, it yields thermodynamic information as well. Our first application is to describe the nematic phases of flexible polymers, and to demonstrate a novel lyotropic transition.