AbstractRadiation‐induced polymerization of water‐saturated styrene (water content 3.5 × 10‐2mole/liter) was carried out in a wide range of dose rate between 1.2 × 103and 1.8 × 107rad/sec, and compared with the polymerization of the moderately dried styrene (water content 3.2 × 10‐3mole/liter). Molecular weight distribution curves of the polymerization products showed that they were generally consisted of four parts, namely, oligomers, radical, cationic, and super polymers. Contributions of the four constitutents to the polymerization and the number average degrees of polymerization (DP) of the four kinds of polymers were calculated by the graphical analysis of the curves. The rate of radical polymerization andDPof radical polymers are independent of the water content; the dose rate dependences of the polymerization rate andDPagree with the well known square root and inverse square root laws, respectively, of the radical polymerization of styrene. The rate of ionic polymerization is directly proportional to the dose rate, but it decreases, at a given dose rate, inversely proportional to the water content of styrene.DPof ionic polymer is independent of the dose rate but decreases with increasing water content. The super polymer ofDPabout 104is not formed in the case of the moderately dried styrene.Gvalues for the initiating radical and ion formation are calculated to be, independently of the dose rate and water content, 0.66 and 0.027, respectively. It was suggested that oligomer was formed in the early stage by the interaction of cation with anion and only those cations which had survived underwent pol
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