Identification of radiation degradation products of soluble fraction of silicone foams

Abstract

It is important to understand the radiation degradation process of silicon foam in radiation aging. Past researches studied the irradiation induced change of mechanical properties. However, the mechanism of micro-degradation is still unclear. In this study, we took a simple pre-treatment of silicone foams with toluene immersion before irradiation. And the results showed that toluene immersion was the key to remove the non-cross-linked oligomers that would interfere with the identification of degradation products. After irradiation, the silicone foams were re-soaked in deuterated toluene solution, and the degradation products were analysed by 1H-NMR, XPS and GPC. The main degradation product of two kinds of silicone foams (methyl vinyl silicone and methyl phenyl silicone) was identified as polysiloxane structures. And the polymerization degree of polysiloxane structures decreased when the irradiation dose increased from 100 kGy to 500 kGy. Theoretical calculations suggested a gradual degradation process, which was in accordance with experiment results.