Physico-chemical modification of polyolefins irradiated by swift heavy ions

The physico-chemical modifications of polypropylene (PP) and polyethylene (PE) induced by 1 MeV/u Xe ions were studied, The irradiated samples were investigated ex situ by means of ultraviolet (UV) spectroscopy, solubility measurements and gel permeation chromatography (GPC). The formation of double bonds, dienes and trienes was observed both in PE and PP, The efficiency of the generation of unsaturated chemical bonds was found to depend on small amounts of aromatic additives in PP. Similarly, the track etch rate in PP increases with increasing concentration of antioxidant molecules, Rough estimates of radiolytic yields of different structures were carried out on the basis of the UV and GPC measurements. It is apparent that there are two basically different processes induced by swift heavy ions passing through the polyolefin: (a) local intratrack reactions; (b) reactions induced by active species leaving the tracks and diffusing into surrounding matrix, The former process leads to the formation of etchable damage, The latter one may cause a mutual influence of tracks even at fairly low ion fluences.