Graft Copolymerization onto Cellulose Derivatives. IV. Graft Copolymerization of Styrene and Styrene—Methyl Methacrylate onto Cellulosic Materials Containing Carbonyl and Carboxyl Groups

Abstract

The graft copolymerization of styrene (St) and styrene+methyl methacrylate (MMA) on to cellulosic materials containing carbonyl and carboxyl groups was carried out using ceric salt as an initiator.Graft copolymerization of styrene: The percent grafting reached a maximum or a levelling-off value at a ceric salt concentration of approximately 10—20 mmol/l, and the values varied with ethanol concentration in the polymerization medium. The percent grafting of styrene onto cellulosic materials increased with the carbonyl group content and decreased with increasing carboxyl group. The apparent activation energy calculated from the initial rate of graft copolymerization was approximately 14.2 kcal/mol. From these results it is deduced that the graft copolymerization is initiated by the redox reaction between the ceric salt and the carbonyl group and the catalytic activity of the initiator decreased due to the reaction between the ceric salt and the carboxyl group.Graft copolymerization of styrene—methyl methacrylate: Total conversion and percent grafting increased with the methyl methacrylate content in the feed, and the polymerization rate was greatly enhanced by the presence of cellulosic materials. The copolymerization of these monomers proceeds by a free radical mechanism. The monomer reactivity ratios r1 (MMA) and r2 (St) of grafted and ungrafted copolymers were determined by using the Fineman—Ross method.From these results, it is considered that the monomer reactivity ratio of copolymer obtained by the copolymerization in the presence of cellulosic materials are different to those carried out in the absence of cellulosic materials. This is due to the interaction between the cellulosic materials and the monomers.