Effects of polymethylvinylsilicone oil with side tetraphenylphenyl groups on the radiation resistance of addition‐type silicone rubber

Abstract

AbstractPolymethylvinylsilicone oil with side tetraphenylphenyl groups (called C2 gum for short) as a low molecular additive was used in two kinds of addition‐type silicone rubber, polymethylvinyl silicone rubber and poly (dimethyl‐diphenyl) silicone rubber, and the radiation resistance of silicone rubbers obtained was investigated by γ‐rays radiation with the dose rate of 117 Gy/min at doses up to 350, 500, and 850 kGy, respectively. Moreover, the average molecular weight between crosslinks and mechanical properties of silicone rubbers after irradiated in air and N2 were determined by toluene‐swelling method and on a XLS‐A rubber test instrument, respectively. The results show that C2 gum can effectively improve the radiation resistance of silicone rubber. When C2 gum is used in poly(dimethyl‐diphenyl) silicone rubber, phenyl groups and tetraphenylphenyl groups may have synergistic effect, and the radiation resistance is improved greatly. The suitable amount of C2 gum used in silicone rubber is 10– 14 phr. The crosslinking density of vulcanizates irradiated in N2 is higher than that of vulcanizates irradiated in air because of the oxidative degradation. The radiation protection mechanism of C2 gum was also discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4144–4148, 2007