Pressure effect on the kinetics of polymerization II : bulk copolymerization of vinyl chloride with propylene and isobutylene

Abstract

The bulk copolymerizations of vinyl chloride with propylene and isobutylene, using benzoyl peroxide as the initiator, were investigated from the kinetic view point in the temperature range of 50°～70℃ and the pressure range 1, 950～3, 900kg/cm^2. It was observed that the copolymerization reaction at constant monomer composition was not preceded by any induction periods, and the polymer yields increased linearly to the reaction time throughout comparatively long runs. And the reaction was accelerated by increasing pressure and temperature. The rate of copolymerization was decreased by increasing mole fraction of propylene or isobutylene in the monomer mixtures. The degrees of copolymerization and the melting points of the copolymers were decreased by increasing mole fraction of propylene or isobutylene in the copolymers, but they were increased by increasing pressure. The monomer reactivity ratios in the copolymerizations of vinyl chloride (M_1) with propylene (M_2) and isobutylene (M_2') at 60℃, were determined as follows ; r_1=2.45±0.12, r_2=0.09, r_1'=1.54±0.02, r_2'=0.08. From these values, Q-and e-values were calculated as follows; Q_2=0.013 to 0.015, e_2=-1.01 to -1.05, Q_2'=0.019 to 0.025, e_1'=-1.20 to -1.30.