Study on damage effects of methyl silicone rubber induced by proton radiation

The damage behaviors of methyl silicone rubber induced by radiation of protons with 150-keV energy were studied. The surface morphology, tensile strength, Shaw hardness, cross-linking density, and glass temperature were evaluated. Positron annihilation lifetime spectroscopy and infrared attenuated total reflection analysis were carried out to reveal the damage mechanism of the rubber. The results show that the tensile strength, Shaw hardness, cross-linking density, and glass temperature of the silicone rubber increase and then decrease with increasing radiation fluence. Analysis indicated that all of the annihilation span τ₃, and the intensity I₃ of the longest lifetime positrons spouses, as well as the free volume V_f, decreased with increasing radiation fluence, under lower radiation fluences, and then increased slowly after the fluence 10¹⁵ cm^-2. The proton radiation would mainly induce cross-linking reactions in the silicon rubber when the fluence is lower, whereas degradation becomes dominant as the fluence increases.