Experimental and Theoretical Study of the Self-Initiation Reaction of Methyl Acrylate in Free-Radical Polymerization

Abstract

Extensive experimental results (measurements of the monomer conversion in the absence of any external initiators) indicating the occurrence of the self-initiation reaction of methyl acrylate (MA) at 120-220 °C are presented. To this date, for the MA, experimentally derived values of the rate coefficients of only propagation, termination, transfer to monomer, and transfer to polymer reactions have been reported. As MA and n-butyl acrylate (nBA) are from the same acrylate family, here, we exploit the family type behavior to obtain the rate coefficients of termination by mid-chain radicals and β-Scission reactions of MA, on the basis of the rate coefficients of the same polymerization reactions of nBA. A new, simple, empirical, gel effect model is also presented. Using these rate coefficients and a macroscopic mechanistic polymerization reactor model, the rate coefficients of MA self-initiation and chain-transfer-to-monomer reactions as well as the parameters of the gel effect model are estimated from the MA conversion measurements.