| Abstract: | To elucidate the reaction mechanism of radiation-induced polymerization of the styrene—silica gel system, the influence of H2O as adsorbed water and inhibitor of cationic polymerization was investigated by two methods. Monomer conversion decreased as H2O increased. In general, percent grafting decreased as H2O increased, but the presence of a small amount of H2O increased the percent grafting. Grafting at 16 Mrad has a maximum value at a water content of about 0.2%. This seems to be due to two effects of H2O: percent grafting increases due to restraint of cationic polymerization by H2O, but the percent grafting decreases due to adsorption water which interrupts the contact of styrene with silica gel. In GPC spectra, the low molecular weight peaks of both graft polymers and homopolymers decreased when H2O was added. The GPC results suggest that the number of positive holes which initiate cationic polymerization is very large. |
