A rheo‐optical study on the reformation of structure in racemic poly(γ‐benzyl glutamate) liquid crystals

Abstract

Abstract Transmitted light intensities were measured by means of the polarized light technique for the nematic liquid crystal phase of racemic poly(γ‐benzyl glutamate) (PBG) in m ‐cresol at 25°C after cessation of steady flow at shear rates ranging from 0.2 to 110 s −1 . Weight‐average molecular weights of PBG used were 1.5, 2.1, and 2.6 × 10 5 , while the concentrations varied between 20, 30, and 40 wt percent. Transmitted light intensities with crossed and parallel polarizers, I x and I | , show wavy changes with time after cessation of steady flow, indicating the retardation decreases with time. An attempt was made to explain experimental results on the basis of a simple model, in which not only relaxation of molecular orientation but also effects of the wall and disclination were taken into account.