Gamma irradiation at low doses (0-50kGy) and ageing effects on PS/PP (80/20) blends with 7.5 wt% SBS. An EPR study

Resumen

In this study PS/PP(80/20) blends at 7,5wt% Styrene-Butadiene-Styrene (SBS), styrolux and stereon respectively, with antioxidant, Recyclostab-811, at 0.1 wt%, γ-irradiated, from a 60Co source, after five years of storage in air at 10, 25 and 50 kGy integral doses of gamma irradiation and a dose rate of 4.8 kGy/h, in air at room temperature, (RT, 24ºC) are investigated by electron paramagnetic resonance (EPR) spectroscopy. The dependence of the line intensity, Ipp and resonance line shape, K on the integral doses, is analyzed. The nature of the free radicals is discussed. The Ipp and K parameters suggest exchange interactions. The RPE analysis shows that the blends under investigation induced a higher formation of free radicals than in the fresh samples γ-irradiated, analyzed in a previous work. Monomolecular processes, investigated in the production of free radicals, occur for both blends studied.