DEGRADATION STUDIES OF SOME POLYESTERS AND POLYCARBONATES .7. POLY(PARA-XYLYLENE CARBONATE)

Previous studies of aliphatic polycarbonates have now been extended to the aliphatic-aromatic polycarbonate, poly(p-xylylene carbonate). The decomposition behaviour of polymer samples made under different conditions has been examined by thermogravimetry, differential scanning calorimetry and thermal volatilisation analysis, using a similar approach to that employed in earlier investigations in this series. The degradation products have been identified and the major product fractions determined quantitatively. It is proposed that thermal degradation proceeds via chain homolysis with elimination of carbon dioxide. At the lowest temperatures, some of the macroradicals produced appear to combine to form p-xylylene ether linkages, whereas others abstract hydrogen atoms to produce shorter chains with methyl and primary alcoholic end groups. The main evolved products at this stage appear as cold ring fraction. The proportion of more volatile degradation products, consisting of carbon dioxide, p-methyl benzyl alcohol and p-tolualdehyde, increases when the degradation temperature is raised above about 300°C. © 1989.