Kinetics of Radical Polymerization. XXIX. Kinetics of Initiation in the Polymerization of Ethyl Acrylate

Abstract

Abstract The rate of initiation has been investigated in the free-radical polymerization of ethyl acrylate at 50°C in two solvents, benzene and dimethylformamide. The rate constant of initiation and the rate constant of the decomposition of AIBN was determined by the inhibition method and nitrogen volumetry, respectively. The rate constant of initiation was found to be constant over the whole range of monomer concentration in benzene solutions, but it proved to depend on the concentration of monomer in dimethylformamide solutions. The latter dependence is not linear. It was pointed out that the change in the rate constant of initiation is due to the solvent effect on the rate constant of decomposition of AIBN, because the factor of radical efficiency is practically constant over the whole range of monomer concentration. The observed relationship between the rate constant of initiation and the molar fraction of monomer was interpreted on the basis of the selective solvation of initiator molecules.