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.