STUDY ON OXIDATION OF POLYMERS TREATED BY HIGH-LET RADIATION

The oxidation of medical silicone rubber and segmented polyether ureth ane which were bombarded with 1 similar to 1.2 MeV Si+ or F+ at the do se of 5 x 10(14) ions/cm(2) was studied. In XPS measurement, it was fo und that the oxygen concentration on the surface of the implanted poly meric membranes had been increasing in three months at least. ESR meas urement showed that some free radicals existed in these membranes and their quantities decreased with time. Chemical analysis proved that pe roxides were generated in the gamma irradiated membranes. The reason f or the increasing of oxygen concentration was that free radicals combi ned with oxygen in the air and produced peroxides on the membrane surf ace. Moreover, in order to demonstrate the radiation mechanism, low LE T (gamma rays) radiation of such polymeric membranes was carried out f or comparison.