Forced oscillations in continuous flow stirred tank reactors with nonlinear step growth polymerization

Abstract

The self-step growth polymerization of RA_f monomers in homogeneous, continuous flow stirred tank reactors (HCSTRs) is simulated under conditions of periodic feed concentration (with frequency ω and amplitude α). By having periodic operation, the polydispersity index of the polymer is found to increase by about 35% over the values at steady state. Periodic operation of HCSTRs is found to lead to gelation only for certain values of the frequency and the dimensionless residence time t^∗. Gelling envelopes have been obtained to give conditions under which HCSTRs should be operated. These envelopes can be described in terms of two critical dimensionless residence times, t^∗_c,1 and t^∗_c,2 such that nongelling operation is always ensured when t∗ < t. For t∗ > t, periodic operation always leads to gelation, and HCSTRs cannot be used. For t^∗ < t^∗ < t^∗_c,1, the gelling behavior is found to depend on the functionality f, amplitude α, and the dimensionless residence time t^∗.