ABSTRACT:A mixture of benzoin, pyridine, and carbon tetrachloride has been found to be an effective initiation system for the polymerization of methyl methacrylate (MMA). The lack of any one component resulted in a remarkably slower rate of polymerization. The a-hydroxy ketone group in benzoin has been shown to be necessary to initiate the polymerization of MMA, by comparison with the results of the polymerizations by benzil, hydrobenzoin, or benzoin methyl ether instead of benzoin. The activation energy of the initiation reaction was calculated to be 12.8 kcal/mol from the overall activation energy of 11.3 kcal/mo!, using the values of the propagation and termination energy in the literature. The small activation energy of initiation suggested that the initiation reaction in this system proceeds through a redox mechanism. The initiation mechanism was proposed on the basis of the results of the kinetics and the product analysis.