Irreversible step growth polymerization having segmental diffusion limitations in HCSTRs-simulation and steady state multiplicity

Abstract

The effect of various parameters on the overall rate constant, number average chain length, and polydispersity index of isothermal, irreversible, step growth polymerization of ARB monomers, exhibiting segmental diffusional limitations and carried out in HCSTRs, are studied. A phenomenological model which has proved useful for chain polymerization is adapted for step growth polymerizations and simulations for several values of the different parameters are carried out. The number average chain length μ_n and the polydispersity index ρ are obtained as a function of the dimensionless time t^∗. It is found that, even though the behavior of μ_n and ρ vs. t^∗ depends on the values of the parameters, the plot of μ_n vs. ρ is unique as expected from statistical considerations. An attempt has been made to investigate the multiplicity of steady states under conditions of infinitely rapid heat transfer from a jacket, using singularity and bifurcation theory. It is found from the analysis that there is no multiplicity of steady states for this system, which is confirmed by simulations using a wide range of parameter values.