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Thermooxidative degradation of polyesters. A contribution to the study of degradation reactions of some types of linear polyesters

1962; Wiley; Volume: 59; Issue: 167 Linguagem: Inglês

10.1002/pol.1962.1205916705

1542-6238

I. Gömöry, O. Mlejnek, J. Štímeľ,

Polymer Science and PVC

Abstract This report is part of an extensive investigation on thermal and thermooxidative degradation. The results of an analysis of the products formed during degradation of the glycol esters of phthalic, maleic, adipic and sebacic acids are discussed. The experiments were carried out in an apparatus especially devised for this purpose. The specimens were subjected to heat treatment at 200, 250, and 300°C. in a current of air for periods varying between 4 and 200 hr. The degradation products were selectively trapped and analyzed by classical methods and by paper chromatography. Some of the degradation products were determined quantitatively, others only qualitatively. Among the degradation products of all types of the polyesters studied were found the monomers, formaldehyde, acetaldehyde, formic and acetic acids, carbon dioxide, carbon monoxide, water and compounds of the type of hydroxyaldehydes, hydroxyacids, and aldehydic acids, which were not identified closer. Furthermore, among the degradation products of glycol adipate and glycol sebacate acids and aldehydes were found with three and more carbon atoms to the molecules. Benzoic acid is a specific product of the degradation of glycol phthalate, as well as cyclopentanone of glycol adipate. The qualitative composition of the degradation products changes little with change in temperature and duration of the experiment. The change in quantity with these factors is greater. From the quantitative standpoint the main degradation products are the monomers, carbon dioxide, carbon monoxide and water. A mechanism for the degradation is proposed which includes consecutive reactions (hydrolysis, esterification, and ressterification) leading to the formation of free endgroups and monomers on the one hand, and radical reactions of which the products are mainly oxidized substances of the structural units of the polymer, on the other.