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

Abstract

Previous studies regarding the bifurcation behavior of continuous stirred tank polymerization reactors have reported a multitude of different nonlinear responses. The nonlinear responses reported most often are steady-state multiplicity and self-sustained oscillatory behavior, which have been confirmed experimentally. Particularly, Freitas Filho, Biscaia, and Pinto (Chemical Engineering Science 49 (22) (1994) 3745–3755) used a generic model to describe the dynamic behavior of continuous free-radical solution polymerizations and were able to show that most reactors can present as many as five distinct steady-state solutions, regardless of the particular chemical system analyzed. The work of Freitas Filho, Biscaia, and Pinto is extended here to show that self-sustained oscillatory responses may also be considered to be generic reactor responses, regardless of the particular chemical system analyzed. The effect of both physico-chemical and operational reactor parameters on the topology of the branches of periodic solutions is also investigated. It is shown that most continuous solution polymerization systems may present regions where limit cycles are present and that the increase of the gel effect decreases the probability of observing sustained oscillatory responses.