LET and dose rate effect on radiation-induced copolymerization of maleimide with styrene in 2-propanol solution

Nakagawa, Seiko*; Taguchi, Mitsumasa; Kimura, Atsushi

N-saturated 2-propanol solutions containing styrene and maleimide were irradiated by electron, proton, He and C-ion beams. The styrene-maleimide copolymer was produced by radical polymerization induced during irradiation. The effects of the radical distribution, which depends on the LET or dose rate, on the molecular weight and the polymer yield were discussed. Both the molecular weight and the polymer yield increased by the decreasing dose rate. These effects increased by irradiation using heavier ions. The polymer yield decreased with the increasing LET value. On the other hand, irradiation at a higher LET value and lower dose rate will produce a polymer with a higher molecular weight. The distribution of radicals in time and space will have an influence on both the molecular weight and the polymer yield.