GAMMA-OXIDATION OF LINEAR LOW-DENSITY POLYETHYLENE - THE DOSE-RATE EFFECT OF IRRADIATION ON CHEMICAL AND PHYSICAL MODIFICATIONS

gamma-Oxidation of linear low-density polyethylene based on hexene and butene was investigated. Irradiation was performed at different dose rates in air (from 2 rad/s to 100 rad/s). Degraded samples were analyzed with IR combined with NO and SF4 derivatizations. Our results showed that the lower the dose rate, the higher the degree of oxidation in terms of gamma-products formation. Ketone species appeared to be the dominant gamma-products. The G values of gamma-product formation were very dependent on the dose rate of initiation. Comparison of the G value ratio of different gamma-products revealed stoechiometry differences. The complex appearance and disappearance of unsaturations was tentatively explained. The modifications of elongation at break induced by gamma-irradiation were monitored by molecular changes in weight. This was not conclusive because changes in elongation at break are inconsistent with changes in M(w)/M(n). (C) 1995 John Wiley & Sons, Inc.