The rigid-rod model for nematic polymers: An analysis of the shear flow problem

The rigid-rod model is capable of predicting several rheological features of rodlike polymers in the nematic phase. The model is formulated in terms of a nonlinear partial differential equation that describes the evolution of an orientational distribution function. The morphological properties and the rheological response of the sample can be determined once the distribution function is known. In this article the rigid-rod model is thoroughly analyzed with tools typical of bifurcation analysis for the case of shear flows. New how regimes, both stationary and periodic, are found and illustrated. The detailed description of the model bifurcation structure allows some considerations about up to date closure approximations. (C) 1999 The Society of Rheology. [S0148-6055(99)01303-0].