The effects of preoxidation of cellulose samples on graft copolymerization in the presence of ceric salt (Ce4+) as an initiator were investigated. The use of Ce4+ as oxidizing agent inhibited the formation of grafts, and the number of grafts decreased as the concentration of Ce4+ in the pretreatment rose. In contrast, the samples oxidized with periodic acid (HIO)4 or hydrogen peroxide (H2O2) tended to show improved initiation characteristics and gave a larger number of grafts than the unoxidized samples. The reactivity of oxidized samples toward Ce4+ was examined and the following results were obtained: The part of easy reactivity decreased in the Ce4+-oxidized samples but it increased in the HIO4-oxidized samples; on the other hand, it did not vary greatly in the H2O2-oxidized samples. Cellulose is probably oxidized to different states by different oxidizing agents, and the reactivity of Ce4+ toward these oxidized samples, as one index, seems to be reflected in the graft copolymerization. It was consequently recognized that the graft copolymerization characteristics of cellulose samples could be improved significantly by proper selection of oxidiation conditions.
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Ogiwara et al. (1973) studied this question.