Copolymerization studies. III. Reactivity ratios of model ethylene copolymerizations and their use in Q–e calculations

Publisher Website
Google Scholar
Abstract
Monomer reactivity ratios for the copolymerization of ethylene (M2) with n‐butyl acrylate, vinyl chloride, vinyl acetate, and vinyl fluoride have been measured at 1000 atm. The respective values and the experimental temperatures are r1 = 11.9, r2, = 0.03, 70°C.; r1 = 3.6, r2 = 0.24, 90°C.; r1 = 1.08, r2 = 1.07, 90°C.; r1 = 0.16, r2 = 4.39, 160°C. Price Q and e values for ethylene calculated from these reactivity ratios, uncorrected for differences in reaction pressure, are 0.03 and −0.43, respectively. New Q and e values (Q0 and e0) for these four comonomers were calculated on the basis of ethylene rather than styrene as the reference monomer. Assuming that the Q0 and e0 values for ethylene are 1.0 and zero, respectively, the monomer's Q and e0 value are as follows: n‐butyl acrylate, 33.3, + 1.02; vinyl chloride, 4.2, + 0.37; vinyl acetate, 0.93, ∼0; vinyl fluoride, 0.25, + 0.6. These Q0 and e0 values give calculated reactivity ratios which are in reasonable agreement with experimental ones. Good agreement is also obtained when the r2 value for the vinyl acetate/ethylene copolymerization is compared with the directly determined rate constant ratio for the addition of an ethyl radical to ethylene and to vinyl acetate, respectively, calculated from previously published data.