A MOLECULAR APPROACH TO THE POLYDOMAIN STRUCTURE OF LCPS IN WEAK SHEAR FLOWS

The viscosity of liquid crystalline polymers (LCPs) in the nematic phase does not approach a Newtonian plateau in the limit of vanishing shear rates. This non-linear effect is probably linked to large distortions of the LCP polydomain, i.e. to a dominant role of the defect structure. To account for spatial distortions inclusive of defects a molecular theory is used, based on a generalized Maier-Saupe potential. The resulting mathematical problem, too complex to be solved exactly, is here suitably simplified. A set of two differential equations is thus obtained, and solutions are found numerically for a representative case. The results indicate that defects can indeed play a leading role in LCP behaviour at low shears by acting as pseudo-walls for director anchoring.