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 poly(butylene terephthalate) and polybutylene oxide, degradation experiments were carried out on this polymer and a model compound (dibutyleneglycol dibenzoate) at 140 degrees C in an oxygen atmosphere. The changes were analysed 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 the basis of the results, an oxidation mechanism for the model compound was proposed and it was concluded that oxidation is initiated at the methylene carbon adjacent to the ether oxygen. The thermal oxidation mainly results in the formation of a stable ester together with a formate, aliphatic and aromatic acids and an alcohol. Based on the similar degradation products found for the model compound and the polymer, it was concluded that the thermo-oxidation mechanisms in these two compounds are similar. (C) 2000 Elsevier Science Ltd. All rights reserved.