The curing of silicone rubber with benzoyl peroxide

Abstract The formation of crosslinks in silicone rubber by benzoyl peroxide was studied by tension and swelling techniques as a function of curing conditions and filler content. The ability of benzoyl peroxide to form crosslinks was found to decrease markedly as the peroxide concentration was increased. The peroxide seems to form crosslinks in an amount independent of the concentration of the silica filler. High crosslink concentrations were found to be necessary to fully utilize the polymer‐filler attachments. Values for the bulk and solution densities of silicone gum and the specific volume of the filler in silicones were determined. The melting point of benzoyl peroxide immersed in silicone gum is reported. The aging of silicone gum at 150°C. in air was found to neither increase nor decrease the number of crosslinks.