Kinetics of Emulsion Copolymerization of Vinyl Acetate and Vinyl Pivalate

Abstract

Vinyl acetate (VAc) and vinyl pivalate (VPi) were homopolymerized and copolymerized by low-temperature redox emulsion polymerization using a manganese chelate as initiator. The polymerization kinetics in these systems were investigated by a mathematical model and estimating the respective kinetic parameters. Among the parameters, the radical entry rate constant, ka, overall rate coefficient for radical desorption, kd, and overall termination rate coefficient in the polymer particle, ktp, were correlated with each other. However, ka, kd, and rate coefficient for the generation of free radicals from the initiator, k1 could not be accurately estimated, since the model was insensitive to these values. The conversion simulated using the estimated parameters showed a reasonable agreement with the experimental results of homopolymerization and copolymerization of VAc and VPi. In a series of experiments of varying initial monomer feed ratio, experimental copolymer composition data more accurately agreed with the simulated values when the partitions of monomers in different phases were considered.