DYNAMIC MODELING OF CONTINUOUS MINIEMULSION POLYMERIZATION REACTORS

The dynamic model developed in this work uses a particle number (PN) a pproach to simulate conventional emulsion (also called macroemulsion) and miniemulsion polymerizations for a plug-flow reactor and a continu ous stirred tank reactor (PFR-CSTR) in series. A major objective of th is work is to observe and analyze the differences between macro and mi niemulsion polymerization as a result of the different nucleation mech anisms (micellar or droplet, respectively). In addition, a simplified steady state CSTR model is developed to provide additional insight int o the effects of droplet nucleation in continuous reactors. It is demo nstrated that the rate of a miniemulsion polymerization in a CSTR is a function of the residence time, the initiator concentration and the i nitial droplet size. In most cases the rate of polymerization using a miniemulsion recipe is greater than that for a conventional emulsion r ecipe at the same operating conditions. Since particle nucleation and growth are coupled for macroemulsion polymerization in a CSTR, the num ber of particles generated in a CSTR is only a fraction of the number of particles generated in a batch reactor. Therefore, a PFR upstream o f the CSTR has a dramatic effect on the rate of polymerization in the CSTR. However, since miniemulsions are dominated by droplet nucleation , it will be shown that the steady state conversion is independent of the reactor configuration.