Fibres from Thermotropic Polyesters: The Use of Chain Modelling in Structural Characterization

Some rigid-chain aromatic polyesters form a ‘liquid-crystal’ nematic mesophase on heating, i.e., they are thermotropic, and exhibit ‘self-reinforcing’ properties when used for specialist mouldings. In contrast to the expanding commercialization of this class of plastics, the utilization of thermotropic polymers for the production of high-performance fibres is in its infancy. This paper illustrates the versatility of a chain-modelling approach, in conjunction with X-ray diffraction, for structural characterization of fibres from the thermotropic poly(p-oxybenzoate-co-p-phenylene isophthalate)s. The models were also used to evaluate the effect of polymer composition on chain stiffness, which is one of the major factors limiting the achievable tensile modulus of such fibres.