COPOLYMERIZATION PROPAGATION KINETICS OF STYRENE AND METHYL METHACRYLATE-REVISITED - 2 - KINETIC-ANALYSIS

In this work, both the implicit penultimate model and a version of the terminal bootstrap model were fitted to extensive (k) over bar(p) dat a covering a temperature range of 17.9-57.2 degrees C, for the copolym erization of styrene and methyl methacrylate (STY-MMA). The average ac tivation energies and frequency factors were also calculated for STY-M MA copolymerizations, and the physical meaning of these parameters was explored. Insufficient composition data at the temperatures studied, together with the extreme sensitivity of the fitted model parameters t o small errors in the kinetic data and the fixed constants, precluded the attachment of any physical significance to the parameters obtained . Nevertheless, two important conclusions can be drawn from this work. Firstly, there appears to be a temperature effect on the average radi cal reactivity ratios (s = s(1) = s(2)), which suggests that there may be an enthalpic component to any penultimate unit effect present. Sec ondly, it appears that the bootstrap model is not a realistic alternat ive to the implicit penultimate model for describing the kinetics of o rdinary copolymerizations such as STY-MMA.