A 1H and 13C n.m.r. study of the products from direct polyesterification of ethylene glycol and terephthalic acid

Low molecular weight samples of poly(ethylene terephthalate), obtained by direct bulk polyesterification of terephthalic acid and ethylene glycol, were studied by 1H and 13C n.m.r. It was possible to determine degrees of conversions of acid and alcohol groups, distributions of free, monoesterified and diesterified terephthalic acid and ethylene glycol and to identify the dimer, trimer and tetramer. Side reactions were also studied.