Particle formation under monomer-starved conditions in the semibatch emulsion polymerisation of styrene. Part II. Mathematical modelling

Models, together with a comparison with experimental data, are presented for the particle nucleation under monomer-starved conditions. In the first model, simplifications were made to obtain analytical solutions. The Smith and Ewart theory was extended to include particle formation under monomer-starved conditions. It was assumed that the rate of particle growth is controlled by the rate of monomer addition. An appropriate correlation for prediction of number of polymer particles in terms of surfactant and initiator concentrations and monomer addition rate was derived as Np=k(as[S])1.0RI2/3Ra−2/3. The second model takes advantage of the new developments in understanding of the kinetics of the water phase and its effects on the radical capture efficiency of micelles. The model accounts for monomer solubilisation in the micelles. According to the model predictions, the size of micelles and their aggregation number are subject to variation during nucleation. The model could successfully predict some important features of particle formation under monomer-starved conditions.