γ- and ultraviolet-radiation-induced solid-state polymerization of maleimide in a few binary systems

Abstract The solid‐state polymerization of maleimide by γ‐ and ultraviolet irradiation was carried out in binary systems with succinimide, maleic anhydride, and acenaphthylene. Polymaleimide obtained from the solid‐state polymerization of maleimide by γ‐rays was amorphous, while that obtained from the solid‐state polymerization by ultraviolet rays was highly crystalline. In the maleimide–succinimide system the rate of polymerization reached a maximum nearly at the eutectic composition when the polymerization was carried out by γ‐irradiation. With ultraviolet irradiation the rate of polymerization became higher with increasing content of succinimide in the feed. In the maleimide–maleic anhydride system a copolymer of both constituents was formed by γ‐irradiation, but almost no homopolymer was produced. On the other hand, two kinds of polymers, a crystalline copolymer and an amorphous one, were produced by ultraviolet irradiation. The results were compared with those obtained from the copolymerization in solution. In the maleimide‐acenaphthylene system the main products with ultraviolet irradiation was the dimer of acenaphthylene.