Selected degradation reactions in polyethylene irradiated with Ar+ and Xe+ ions

Polyethylene (PE) was irradiated with 63 keV Ar+ and 156 keV Xe+ ions (R-P = 100 nm for both ions) to the fluences from 1 x 10(13) to 3 x 10(15) cm(-2). Degradation processes in the PE surface layer, modified by the ion irradiation, were characterized by measuring depth profiles of residual hydrogen and incorporated oxygen (RBS/ERD techniques), free radical concentration (EPR) and conjugated double bond concentration (UV-VIS). Dehydrogenation due to release of a part of volatile degradation products was observed. Interactions among free radicals, produced along the ion path, result in a creation of new, conjugated double bonds. Some of free radicals react with oxygen coming from ambient atmosphere in the ion implanter and in this way, oxidized structures are produced. Dehydrogenation of PE chains and degradation of oxidized structures, appear to be related to the energy locally deposited via ion electronic energy loss. (C) 2000 Elsevier Science Ltd. All rights reserved.