Methyl ethyl ketone peroxide as an initiator in the polymerization of vinyl monomers

Abstract

A systematic investigation was undertaken of the kinetics of polymerization of styrene and methyl methacrylate in bulk as well as in solutions of benzene, toluene, methyl ethyl ketone and ethyl acetate and of methyl acrylate in ethyl acetate with methyl ethyl ketone peroxide (MEKP) as initiator at 65–80°C. The decomposition of MEKP in ethyl acetate at 70 and 80°C. was studied and the specific rate constants for spontaneous as well as induced decomposition have been evaluated. Transfer coefficients for the monomer, catalyst, and solvent with their respective activation energies have been determined. The rates of initiation have been evaluated by measuring rates and the degree of polymerization for the monomers under study. The catalyst efficiencies in the polymerization of the monomers have been evaluated from the rates of initiation and the rate of decomposition of the catalyst. It is found that the initiator MEKP is comparable to Bz₂O₂ and azobisisobutyronitrile in its catalyst efficiency, while its capacity for chain transfer is found to be intermediate between the nontransferring initiators like azobisisobutyronitrile and the highly transferring initiators such as cumene hydroperoxide. That the effect of solvents on the various rate constants such as termination and initiation appears to be of no inconsiderable importance has been inferred.