Studies of the vapour-phase polymerisation and oxidation of styrene

Abstract

The polymerisation and oxidation of styrene vapour have been studied, both in the absence and presence of the liquid monomer. When liquid styrene is absent, no appreciable polymerisation takes place in the gas phase below 500°C, at which temperature pyrolysis starts to occur; but styrene reacts with oxygen above 300°C, undergoing some polymerisation simultaneously with oxidation. The presence of the polymerising liquid monomer causes styrene vapour-air mixtures to ignite under conditions where they would not normally do so, the promoting influence being more marked at low pressures. On the one hand, the liquid styrene accelerates reaction due presumably to its acting as a source of the chain-carriers involved in the combustion of the monomer. This accelerating effect appears however to be partially offset by the temporary cooling of the reactant vapour caused by introduction of the relatively cold liquid.