Radiation‐induced reactions with cellulose. III. Kinetics of styrene copolymerization in methanol

The kinetics of the radiation‐induced grafting of styrene to cellulose in methanol have been studied in air at dose rates of 0.007, 0.014, and 0.078 Mrad/hr. in 60Co and spent fuel element facilities. The variables affecting rate of grafting include monomer concentration, radiation dose rate, and total dose. Grafting reaches a maximum at 60–70% by volume methanol in styrene. The results have been interpreted in terms of possible grafting mechanisms, including charge‐transfer intermediates; however, a complete mathematical treatment of the data is not possible at present because of the absence of appropriate swelling data for cellulose in mixtures of styrene and methanol. Poor grafting observed in solutions of up to 10% monomer is attributed to radical scavenging (predominantly from the solvent) by the monomer leading to the formation of scavenged products including homopolymer. Rate of grafting falls off for solutions above 80–90% monomer concentration and radical scavenging by monomer radicals is again postulated to account for the observed behavior.