THERMOTROPIC POLYESTERS - STRUCTURE OF POLY(P-OXYBENZOATE-CO-M-PHENYLENE TEREPHTHALATE) FIBERS

Wide-angle X-ray diffraction techniques are employed to characterize t he structure of 'as-made' and heat-treated fibres produced from nemato genic poly(m-phenylene terephthalate), where the molar fraction of the disruptor m-phenylenedioxy units is 0.25. As in the case of previousl y investigated poly(p-phenylene isophthalate)s, the 'as-made' fibres c onsist of a paracrystalline array of chains aligned along the fibre ax is. Heat-treated fibre contains a mosaic of thin crystallites, consist ing of m-phenylene terephthalate sequences, embedded in a paracrystall ine matrix. A non-planar chain conformation, arising from the presence of m-phenylenedioxy units, is reflected in the shortening of the crys tallographic repeat in the chain direction compared with that found fo r the poly(p-phenylene isophthalate) fibres.