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