AbstractThe mutual irradiation technique in vacuo has been used to study the grafting (G) of styrene to regenerated cellulose film in a dioxan/water medium and the simultaneous homopolymerization (H). The initial rates RGand RHare both found to be directly proportional to the concentration of styrene, but the ratio of the rate constants kP2/ktis ca. 105times greater in grafting than in homopolymerization (58 cf. 3.3 × 10−41. mole−1sec−1). Bimolecular termination is indicated in both cases by the observed dependences of RGand RHon (intensity)0.5. The degrees of grafting utilized to determine RGwere shown to be apparent values only, since extraction of ungrafted cellulose yielded products in which the true degrees of grafting were all some ten times greater.From ESR spectra of cellulose irradiated in air a value of 1.6 was derived for G (radical) and there was some evidence of scission. Corresponding spectra of cellulose irradiated in vacuo gave G(radical) = 2.9, but no evidence of scission. The radical, formed by hydrogen abstraction, was shown to be located at the C1atom. However, evidence for scission in cellulose irradiated (in the presence of dioxan/water) in vacuo and in air was provided by measurements of intrinsic viscosity, values of 13.5 and 24.6, respectively being derived for G(sci