X-Ray Diffraction Study of Thermotropic Liquid Crystalline Polyesters and Diester Model Compounds.

Abstract : Two nematic liquid crystalline polyesters were examined by x ray diffraction following quenching from the nematic temperature in a magnetic field of 15 tesla. It was not possible to quench an aligned nematic glass; instead a polycrystalline phase showing some preferred orientation or an unoriented nematic melts yielded monodomain nematic diffraction patterns with one resembling that of a fiber (crystalline) photograph while the other showed good nematic alignment which could be enhanced slightly by annealing. A series of Siamese-twin diester model compounds also were examined at their respective nematic temperatures in a magnetic field of compounds also were examined a their crystalline phase at room temperature. All displayed well-aligned nematic monodomains above the crystallization point. Keywords: X ray diffraction, Thermotropic liquid crystalline polyesters.