Simulation of reversible AA + B'B" polycondensations in wiped film reactors

Abstract

Wiped-film reactors carrying out AA + B'B" type reversible polycondensations (where A, B', and B" are functional groups, with B' and B" reacting with A at different rates) have been simulated. The governing mass balance equations have been solved for two transport models of this reactor (one by Ault and Mellichamp and the other by Amon and Denson) using a combination of finite difference and the Runge-Kutta methods. The increase in the number-average chain length μ_n of the polymer formed in the reactor is computed as a function of the various rate constants and the parameters characterizing the reactor. μ_n is found to be most sensitive to the surface area of the film and to the temperature used, both for the equal reactivity as well as for the unequal reactivity cases. For the latter, the effect of the reactivity ratio for the forward rate constants is more significant than that of the equilibrium constants. Results of the two models are also compared under similar conditions and it is found that under equivalent conditions, the Amon-Denson model gives slightly higher μ_n than the Ault-Mellichamp model.