THEORY AND SIMULATION OF OPTICAL BANDED TEXTURES OF NEMATIC POLYMERS DURING SHEAR-FLOW

Simulations of banded texture optical phenomena during shearing of liquid crystalline polymers are presented. A computational analysis of the polarized light transmission pattern for the nonhomogeneous orientation structure of a representative nematic polymer during shear start-up flow is presented. Simulations show that the shear-induced structure that gives rise to the banded texture is an array of tubular orientation inversion walls whose axes are normal to the flow direction. The corresponding optical computations are in good agreement with the experimentally observed banded textures of light transmission under crossed polars of sheared poly(gamma-benzyl-L-glutamate) (PBLG) (Yan, N. X.; Labes, M. M. Macromolecules 1994, 27, 7843). The computer simulations show the intimate relation between the light transmission pattern and the tubular orientation inversion wall array and, hence, shed a new light on the origin of this ubiquitous phenomenon.