Rheo-Optics of an Augned Thermotropic Liquid Crystalline Polymer

Rheo-optical studies on aligned and unaligned melts of a main chain thermotropic polyester with flexible spacers are discussed in terms of the predictions of the Ericksen-Leslie equations. It is shown, using conoscopy, that the director is flowaligning at temperatures close to TNI and nonflow-aligning close to a smectic to nematic (TSN) phase transition. The implications of these results are discussed in terms of the change in sign of one of the Leslie viscosity coefficients and interpreted in the framework of the Ericksen-Leslie Theory.