Imaging of Textures and Defects of Thermotropic Liquid Crystalline Polyesters by Electron Microscopy

Abstract

There is strong interest in observing textures and defects in liquid crystalline polymers (LCP), because of their influences on the rheological and optical properties of these materials. The defects, called disclinations, are hypothesized to give rise to the non-Newtonian flow observed at low shear rates.¹ Disclinations are line singularities in the orientation of the molecular director (n(r)). The orientation as a function of position following an imaginary loop around the disclination changes by nπ. The strength of a disclination is defined as nπ/2π. Disclinations of strength ±1/2 and ±1 have been observed. The disclination line, or core as it is called, has a small but finite volume supposed to contain isotropic material.