Effect of intramolecular transfer to polymer on stationary free radical polymerization of alkyl acrylates, 2 - Improved consideration of termination

Procedures are developed to estimate kinetic rate coefficients from available rate data for the free radical solution polymerization of butyl acrylate at 50 degrees C. The analysis is based upon a complete mechanistic set that includes the formation of mid-chain radicals through backbiting and their subsequent reaction, and contains no assumptions on how the rate coefficient for cross-termination of mid-chain and end-chain radicals is related to the two homo-termination rate coefficients. After a thorough statistical analysis, the results of the fitting are combined with other recent literature data to provide a complete set of individual rate coefficients for the butyl acrylate system. Monomer addition to a mid-chain radical is estimated to be slower than addition to a chain-end radical by a factor of more than 400. The termination of two mid-chain radicals is estimated to be two orders of magnitude slower than termination of two end-chain radicals, with the cross-termination rate coefficient close to the geometric mean.