AbstractThe graft copolymerization of ethyl acrylate from methanol‐water solutions with γ‐irradiated cotton cellulose I and II was investigated by electron spin resonsance spectroscopy and by the formation of cellulose‐poly(ethyl acrylate) copolymer. The rate and extent of graft copolymerization reactions in these heterogeneous systems were dependent on conditions of storage of the irradiated celluloses prior to reaction, the composition of the methanol‐water solutions, reaction time, agitation during the reaction, and cellulose crystal lattice type. Agitation of the heterogeneous system during reaction decreased both the rate and extent of copolymerization. From water the extent of copolymerization of ethyl acrylate with irradiated collulose I was greater than with cellulose II; from methanol the extent of copolymerization with irradiated cellulose II was greater than with cellulose I. From methanol(40 vol‐%)‐water(60 vol‐%) maximum extent of copolymerization occurred with both irradiated celluloses; however, the extent of copolymerization was less with irradiated cellulose II than with cellulose I. The extent of copolymerization was directly related to the initial concentration of free radicals in the irradiated cellulose. However, a fraction of the radicals, about 10% of the maximum concentration in cellulose obtained at a dosage of 5.2 × 1019eV/g, was apparently in the highly ordered regions of the cellulosic structure. These radicals were not scavenged and did not initiate copolymeriz