Critically evaluated rate coefficients for free-radical polymerization, 2: Propagation rate coefficients for methyl methacrylate

Pulsed-laser polymerization (PLP) in conjunction with molar mass distribution (MMD) measurement is the method of choice for determining the propagation rate coefficient k_p in free-radical polymerizations. The authors, members of the IUPAC Working Party on Modeling of kinetics and processes of polymerization, collate results from using PLP-MMD to determine kp as a function of temperature T for bulk free-radical polymerization of methyl methacrylate at low conversions and ambient pressure. Despite coming from several different laboratories, the values of k_p are in excellent agreement and obey consistency checks. These values are therefore recommended as constituting a benchmark data set, one that is best fitted by k_p = 10^6,427 L · mol^-1 · s^-1 exp(-22, 36 kJ · mol^-1/R · T) The 95% joint confidence interval for these Arrhenius parameters is also given. In so doing, we describe the most appropriate statistical methods for fitting k_p(T) data and then obtaining a joint confidence interval for the fitted Arrhenius parameters. As well, we outline factors which impose slight limitations on the accuracy of the PLP-MMD technique for determining k_p, factors which may apply even when this technique is functioning well. At the same time we discuss how such systematic errors in k_p can be minimized. a) Part 1: cf. ref. 1).