LUMINESCENCE FROM GAMMA-IRRADIATED AND BETA-IRRADIATED HDPE AND LLDPE

The luminescence of polyethylene (high density polyethylene (HDPE) and linear low density polyethylene (LLDPE)) induced by ionising irradiat ion has been studied. The effects of filling materials, irradiation do se and dose rate on the luminescence have been investigated. For fresh ly irradiated samples, both unfilled and filled, the luminescence was concluded to consist predominantly of thermoluminescence (TL). Upon su bsequent ageing, the contribution of TL was found to decrease due to i ts decay with time after irradiation. Light emission was found to incr ease in the later stages of ageing, for irradiated and also for unirra diated samples. This light was interpreted as chemiluminescence (CL), emitted as a result of polymer oxidation. The maximum of the CL was hi gher for irradiated than for unirradiated polyethylene, indicating tha t the ionising radiation gave rise to an increased amount of oxidation products. Thus, CL has been shown to be a feasible technique in studi es of radiation-induced oxidation.