Thermo-oxidative studies of poly(ether-esters) 2. Copolymer of poly(butylene terephthalate) and polybutylene oxide

To determine the thermo-oxidative degradation mechanism of a copolymer of p oly(butylene terephthalate) and polybutylene oxide, degradation experiments were carried out on this polymer and a model compound (dibutyleneglycol di benzoate) at 140 degrees C in an oxygen atmosphere. The changes were analys ed using various analytical techniques, such as oxygen uptake measurements, measurement of CO/CO2 formation, H-1 and C-13. NMR, FT-IR and GC-MS. On th e basis of the results, an oxidation mechanism for the model compound was p roposed and it was concluded that oxidation is initiated at the methylene c arbon adjacent to the ether oxygen. The thermal oxidation mainly results in the formation of a stable ester together with a formate, aliphatic and aro matic acids and an alcohol. Based on the similar degradation products found for the model compound and the polymer, it was concluded that the thermo-o xidation mechanisms in these two compounds are similar. (C) 2000 Elsevier S cience Ltd. All rights reserved.