Abstract: The ESRspectra of all samples prepared in the previous paper are obtained at room and low temperature (liquid nitrogen 77K). The quartet with a hyperfine splitting of 23 gauss is due to radicals of type · CH₃;the triplet with a hyperfine splitting of 22 gauss,due to · CH-Si≡ and the singlet due to ·Si≡ or · O-Si . The spectrum differs with the change in the silica filler content.The radicals produced in the irradiated PMVSare stable and decay slowly on keeping the samples at 77Kor room temperature, while warming the samples from 77K to room temperature, the radical .signal becomes weaken. Furthermore,the radicals in all samples almost disappear over 100℃ for 2h or more. These samples have a stable gel content at room temperature. In this way, the radicals in radiation crosslinked PMVScan be cleared up.The radiation behavior of PMVSand the influence of silica filler on the crosslinking are also studied in present work. The radicals in silica filler are observed. These radicals may couple with the main chain scission radicals resulted from mechanical processing to form crosslinks. The coupling of radicals has more chances in radiation crosslinking process, and PMVSwith filler does crosslink easier than PMVSwithout filler. So the enhancement of silica filler to radiation crosslinking of PMVSis mainly chemical mechanism.

Key words: ESR spectra, Poly(methyl vinylsiloxane), Silica, Radiation crosslink