Analysis of multiphase polycarbonate polymerization in a semibatch reactor

A physical and chemical model that describes the interfacial condensation of bisphenol-A to polycarbonate in a multiphase gas-liquid-liquid semi-batch reactor is presented. The particular polymerization kinetics model consists of initiation, propagation and termination reactions between dissolved bisphenol-A monomer, phosgene gas, a phenolic polymer chain growth stopper and various resulting polymer species. Using these kinetics, a physical model for a semi-batch stirred tank reactor is developed. The model accounts for finite liquid-liquid and gas-liquid mass transfer resistances and includes either plug-flow or complete backmixing of the gas bubbles as options for the gas flow pattern. The model equations are solved using the z-transform method from which the polymer MWD and the moments of the polymer MWD are obtained. The utility of the model as a quantitative means of assessing the effect of various kinetic and transport parameters on the polymer MWD is examined for a particular case.