Critically evaluated rate coefficients for free-radical polymerization, 3. Propagation rate coefficients for alkyl methacrylates

Pulsed-laser polymn. (PLP) in conjunction with the anal. of the mol. wt. distribution (MWD) via size-exclusion chromatog. (SEC) remains recommended by the IUPAC Working Party on Modeling of polymn. kinetics and processes as the method of choice for the detn. of propagation rate coeffs., kp, in free-radical polymn. Kp data from PLP-SEC studies in several labs. for Et methacrylate (EMA), Bu methacrylate (BMA) and dodecyl methacrylate (DMA) bulk free-radical polymns. at low conversion and ambient pressure are collected. The data fulfill consistency criteria and the agreement among the data is remarkable. These values are therefore recommended as constituting benchmark data sets for each monomer. The results are best fit by the following Arrhenius relations: [Equation Omitted] [Equation Omitted] [Equation Omitted]. For the methacrylates under investigation kp increases with the size of the ester group. For example, in going from MMA to DMA, kp at 50 DegC is enhanced by a factor of 1.5.