Features of the Polymerisation Kinetics of Methyl Methacrylate in the Presence of Initiators of Different Structure

Abstract

The thermographic method was used to study the polymerisation kinetics of methyl methacrylate (MMA) at 60°C in the presence of initiators: dicyclohexylperoxy dicarbonate (CPC), azoisobutyric acid dinitrile (AIAD), benzoyl peroxide (BP), and lauryl peroxide (LP). In the region of initial conversions, the mechanism of chain growth limitation is bimolecular, and the order of the reaction with respect to the initiator is 0.5. In the region of the maximum polymerisation rate, the order of the reaction with respect to the initiator is greater than 0.5 and varies according to the initiator concentration. The mechanism of chain growth limitation at extensive conversions is monomolecular. Additional initiation occurs through degradation of the polymer, governed by the formation of stresses during polymerisation. The observed differences in the polymerisation kinetics in the MMA–CPC system are connected with the redistribution of initiator in regions with inhomogeneous concentrations of monomer and polymer.