DYNAMICS OF CONTINUOUS ISOBUTYLENE CATIONIC POLYMERIZATIONS

Polyisobutylene can be produced in either continuous cationic precipit ation or solution polymerization reactors. It is known that the open-l oop behavior of polymerization reactors may be very complex and may le ad to oscillatory behavior, which is usually caused by thermal positiv e feedback (due to the large heats of reaction of polymerization react ions) and high viscosity effects (such as the gel effect in radical po lymerization reactors and the decrease of heat transfer coefficients a t high polymer concentrations). Oscillatory behavior may be observed i n industrial isobutylene reactors, and it is intended to know whether these oscillations are inherent to the kinetic mechanism. Based on pub lished experimental data, mathematical models are developed for both s olution and precipitation processes. Steady-state solutions are calcul ated and steady-state stability is analyzed. Dynamic simulations and s tability results reveal that only single stable steady-state solutions are possible for such reactors at usual operation conditions, which m eans that oscillatory behavior is not intrinsic to the reaction mechan ism. (C) 1996 John Wiley & Sons, Inc.