REACTIVITY RATIOS FOR GRAFTING OF VINYL-ACETATE AND METHYL ACRYLATE MIXTURES ONTO CELLULOSE AT HIGH CONVERSIONS

The heterogeneous graft copolymerization of a mixture of vinyl acetate (VAc) and methyl acrylate (MA) onto cellulose was carried out in an aqueous medium through a radical mechanism. Copolymerization led, as usual, to the simultaneous formation of grafted and non-grafted poly(vinyl acetate-co-methyl acrylate). The reactivity ratios of VAc and MA were determined from high-conversion data by using an integrated form of the copolymerization equation. Values of the reactivity ratios for VAc (r1 = 0,020) and MA (r2 = 6,750) were calculated. The capacity of the methods for determining reactivity ratios based on the differential copolymerization equation is discussed for the present copolymerization system. Some significant characteristics of the copolymer and the copolymerization reaction are deduced from the copolymerization parameters. It is concluded that the polymerization sites of the grafting and homopolymerization reactions are identical. Also, the present aqueous dispersion technique yields similar results as bulk polymerizations.