Free radical bulk polymerization of styrene: Simulation of molecular weight distributions to high conversion using experimentally obtained rate coefficients

Previously obtained experimental conversion dependences of the propagation rate coefficient (k(p)), the termination rate coefficient (k(t)) and the initiator efficiency (f) for the free-radical bulk polymerization of styrene at 70degreesC have been used to stimulate the full molecular weight distributions (MWD) to high conversion using the software package PREDICI, providing a robust test of the kinetic model adopted. Satisfactory agreement with the experimental MWD's (GPC) was obtained up to approximately 70% conversion. Beyond 70% conversion, the high MW shoulder that appears was correctly predicted, although the amount of such polymer was somewhat underestimated. This discrepancy is believed to probably have its origin in experimental error in the conversion dependencies of k(p), k(t), and f, in particular k(t), that were employed in the simulations, rather than indicate a more fundamental short-coming of the model employed.