A further study on the crystallization and melting behavior of liquid crystalline copolyesters based on modified poly [(p-hydroxybenzoic acid)-co-(ethylene terephthalate)]

In a previous investigation of the: crystallization and melting behavior of liquid crystalline PET/HBA/HQ/TPA copolyesters, which were prepared by the incorporation of p-hydroxybenzoic acid (HBA), hydroquinone (HQ), and terep hthalic acid (TPA) into poly(ethylene terephthalate ephthalate) (PET), we r eported that,they are more crystal-line than PET/HBA copolyesters. Introduc tion, of HQ/TPA disrupts longer rigid-rod sequences formed by HBA, enhancin g macromolecular motion and increasing crystallization rate and, crystallin ity. In particular, PET/HBA/HQ/TPA copolyesters may also exhibit two endoth ermic fusion peaks under certain crystallization conditions. This; paper is a further study of, the, crystallization and melting behavior of a PET/HBA /HQ/TPA copolyester with molar ratio of 40/20/20/20. The double-peak differ ential scanning calorimetry melting endotherms. from isothermally-crystalli zed samples have been scrutinized in terms of two, hypotheses: (i) they are associated: with, two, distinct morphologies or crystals; (ii) they are re lated to melting, and recrystallization effects. Our data from a, combinati on of differential scanning calorimetry wide angle X-ray diffraction, and d ensity techniques, support the second hypothesis, and are not consistent wi th the first one.