The Effect of Chain-kinks on the Phases and Structure of a Series of Thermotropic Liquid Crystal Polyesters Prepared by a Novel Non-aqueous Dispersion Route

Abstract

A series of aromatic polyesters have been synthesized by a non-aqueous dispersion route, comprising monomer residues of x parts p-hydraxybenzoic acid and (1- x)/2 parts of each of hydroqzcinone and isophthalic acid. The nascent polymers are in a novel particulate form with a molecular organization that differs front melt-processed polymer. By decreasing x, increasing amounts of kinked meta phenyl units are intro duced into an otherwise para-phenyl chain. The phase diagram deduced from DSC and hot stage microscopy shows the series spans frorn isotropic to liquid crystalline behaviour with an interesting borderline region. Three crystal forms are observed. One is associated with cooling from the mesophase and contains the kinked isophthalic acid units; this exhibits a relatively high Enthalpy of Fusion. Mouldings from the series show a gradual change in modulus with x.