STUDIES ON CO[POLY(ETHYLENE TEREPHTHALATE-P-OXYBENZOATE)] THERMOTROPIC COPOLYESTER - SEQUENCE DISTRIBUTION EVALUATED FROM TSC MEASUREMENTS

Relaxation!transition behaviours for copolyesters made from poly(ethyl ene terephthalate) (PET) and p-acetoxybenzoic acid (POB) have been cha racterized by thermally stimulated current (TSC) measurement. The sequ ence distribution, in terms of the degree of blockiness, in dual chemi domains of POB/PET copolyester is simulated from a model developed by us to predict the probability between block sequence and random sequen ce under a given composition and measuring condition. It is found that the degree of blockiness, a measure of sequence distribution, under t he same polarization temperature generally increases with increasing P OB content in the POB/PET copolyester. For copolyesters of the same co mposition, the degree of blockiness shows a large decrease after solid -state polymerization when high molecular weight PET is used, whereas it shows only a small decrease or an increase after solid-state polyme rization when PET of lower molecular weight is used. It is concluded t hat the change in the degree of blockiness caused by the solid-state p olymerization of copolyesters is dependent on the molecular weight of sequences of the PET moiety in the structure.