Solid State Polymerization Under High Pressure

Abstract

Abstract The radiation-induced polymerizations in three different types of monomers under high pressure have been investigated. First, radiation-induced solid state reaction in several radical type polymerization systems has been studied under pressure up to 6,000 atm. It was pointed out from the experiments that only the propagation reaction is affected by applied pressure, and the reaction in the crystal matrix is suppressed, while the reaction in the amorphous matrix is accelerated by pressure. Second, polymerization of several monomers, such as acrylonitrile, methacrylonitrile, at low temperatures has been studied under high pressure up to 7,000 atm. From these studies, it was shown that the polymerization of acrylonitrile can take place without an appreciable change of the volume at very low temperatures below the transition point at about − 130°C, and that the polymerization cannot take place in a definite temperature region, under a high pressure, from the melting point at the pressure to a transition point at about − 100°C at the same pressure, indicating that a change of crystal structure due to the phase transition gives an extremely large influence to the reactivity of monomer crystals. Finally, polymerization of cyclic monomers such as trioxane, diketene β-propiolactone and propylene oxide, has been investigated. From the investigation, it was observed that the polymerization of diketene and β-propiolactone can be accelerated by applying pressure, while the polymerization of trioxane is retarded by applying pressure. The pressure effect on solid state reaction is compared among three different types of polymerization.