Elastomer reinforcement from a glassy polymer polymerized in situ

Abstract

Abstract Cross‐linked networks of poly(dimethylsiloxane) were swelled with styrene containing benzoyl peroxide. Polymerization of the styrene in situ, by increasing the temperature, gave novel elastomeric composites. Scanning electron micrographs suggest that low concentrations of styrene (∼ 14 wt.%) gave primarily low‐molecular‐weight polystyrene (PS), which acted merely as a diluent in the networks. Larger amounts gave PS which phase separated into glassy particles having diameters in the approximate range 0.05–1.5 μm. In these cases, an increase in wt.% PS gave networks showing large increases in ultimate strength, which was to be expected. Surprisingly, there were also increases in maximum extensibility, which usually decreases in response to modifications which increase the ultimate strength.