PHENOMENOLOGICAL THEORY OF TEXTURED MESOPHASE POLYMERS IN WEAK FLOWS

A macroscopic viscoelastic model for incompressible, isothermal, homog eneous lyotropic mesophases exhibiting the nematic polydomain texture is presented. Under equilibrium static conditions the model describes a three dimensional tessellation, where each region or nematic domain has a characteristic size and orientation, and where the polydomain te xture has a random orientation. Close form expressions that define the characteristic texture size and the number of randomly oriented domai ns are given. When subjecting the model lyotropic liquid crystalline p olymer displaying the polydomain texture to a steady rectilinear shear flow, the predicted characteristic texture size decreases with increa sing shear rates. The power law scaling relations of texture size with shear rate are in excellent agreement with the experimental measureme nts. The steady shear flow orientation predictions, characterized by a positive shear dependent alignment angle and a low orientation, are i n agreement with experimental data.