Periodic oscillations in continuous free-radical solution polymerization reactors - a general approach

Previous studies regarding the bifurcation behavior of continuous stirred t ank polymerization reactors have reported a multitude of different nonlinea r responses. The nonlinear responses reported most often are steady-state m ultiplicity and self-sustained oscillatory behavior, which have been confir med experimentally. Particularly, Freitas Filho, Biscaia, and Pinto (Chemic al Engineering Science 49 (22) (1994) 3745 -3755) used a generic model to d escribe the dynamic behavior of continuous free-radical solution polymeriza tions and were able to show that most reactors can present as many as five distinct steady-stale solutions, regardless of the particular chemical syst em analyzed. The work of Freitas Filho, Biscaia, and Pinto is extended here to show that self-sustained oscillatory responses may also be considered t o be generic reactor responses, regardless of the particular chemical syste m analyzed. The effect of both physico-chemical and operational reactor par ameters on the topology of the branches of periodic solutions is also inves tigated. It is shown that most continuous solution polymerization systems m ay present regions where limit cycles are present and that the increase of the gel effect decreases the probability of observing sustained oscillatory responses. (C) 2001 Elsevier Science Ltd. All rights reserved.