DEGRADATION EVALUATION BY RADIOCHEMICAL YIELDS

Degradation of thermoplastics can be evaluated by radiochemical nil ld s of oxygenated products formed during gamma irradiation in air. Stabl e structures whose concentrations were measured by infra red spectrosc opy show unlike behaviour expressed by dose dependence of normalized a mounts of C=O and C-OH to 100 eV absorbed energy. In spite of sol-gel content which presents minimum values for all proportions of EPDM/PSt, namely 75/25, 50/50 and 25/75, at a ratio of D-g/D=0.2, formation yie lds of oxygenated products change in a different manner. It was notice d that the formation rate of C-OH is much greater fbr the first stage of irradiation than later. In contrast, the increase of C=O() concentr ation shows different shaped curves. (C) 1997 Elsevier Science Ltd.