Thermal stability of some aromatic polyesters and poly(ester carbonates)

The thermal stability of some hydroxyl-terminated poly(bisphenol A tere- or isophthalates) and their corresponding poly(ester carbonates) made by subsequent coupling with phosgene has been investigated by thermogravimetry. Samples have been studied in nitrogen or air using constant rates of temperature rise or isothermal conditions.The isophthalate-containing polyesters are more thermo-oxidatively stable than their terephthalate analogues and molecular weight has a significant effect on stability. In contrast, there is little difference in the thermal stability of the poly (isophthalate carbonates) and the poly(terephthalate carbonates) and the stability of the latter is relatively independent of the ratio of the diester to carbonate group content. The stability of the poly(terephthalate carbonates) is also relatively insensitive to end-group modifications.