Processing of Thermotropic Liquid Crystalline Polymers and Their Blends.

摘要

Preliminary studies were conducted on the hot-drawing of aromatic copolyester LCP fibers (KU-9211 and KU-9221 from Bayer A. G.) and blends of one of these with an aliphatic containing LCP (PET/PHB60 from Tennessee Eastman). The properties of the hot drawn fibers were characterized by measuring storage moduli, E, and molecular orientation parameters, <S>, as a function of draw ration. A model was developed to correlate both (s) and 'E' with draw ratio by taking account of thermal relaxation during the drawing process. Agreement between experimental data and the model was obtained by use of a single dimensionless parameter, alpha, which depends on the processing conditions. An in-situ LCP composite of KU-9211 and PET/PHB60 was generated by a combination of blending and hot-drawing and then characterized using SEM, TEM and single-fiber mechanical tests. The dispersed phase consists primarily of highly oriented, 0.5 to 2.0 micrometer diameter rigid-rods of aromatic fibers imbedded in a matrix of predominantly aliphatic LCP fibrils with diameters in the range of 20 to 50 nm. Morphological evidence suggests a strong interfacial adhesion between the dispersed and the matrix phases in this specific system. (aw)