Study on co[poly(butylene terephthalate-p-oxybenzoate)] thermotropic copolyester. I. Composition analysis and sequence distribution

Copolyesters made from Poly(butylene terephthalate) (PBT) and p-acetoxy-ben zoic acid (PAB) have been examined in solution by proton nuclear magnetic r esonance (NMR) spectroscopy. Proton NMR spectra of solutions have shown tha t the sequence distribution for POB/PBT copolyesters can be described in te rms of a probability model in which POB (p-oxybenzoate) has a chance that i s almost random of being bonded to another POB in the copolyesters, with PO B content ranging from 20 to 40 mol %. From the experimental data, we can p redict that the higher the content of POB in copolyester is, the larger the deviation from randomness of sequence distribution is. (C) 2000 John Wiley & Sons, Inc.