Photodegradation of polyethylene: comparison of various photoinitiators in natural weathering conditions

Thin polyethylene films containing various additives as photoinitiators have been photooxidized in natural weathering conditions and under accelerated conditions using xenon radiation. The photoinitiators include iron carboxylate, allyl ether and ester and various aryl- and aralkylketones. Main chain scission is the dominant process in natural weathering conditions. The formation of cross-links is nevertheless detected by GPC in all cases except with iron carboxylate. Fragmentation of the films is observed at high doses in all cases. When xenon radiation is used, cross-linking is much more important, as indicated by the broadening of the MWD and the lowering of the OD at 1715 cm-1. The difference between photodegradation by solar light and by xenon irradiation was assigned to a temperature effect and interpreted using the classical spontaneous mechanism of polyethylene degradation. © 1992.SCOPUS: ar.j