Although both emulsion and suspension polymerization processes are performed in heterogeneous media, each process presents its own typical characteristics, such as the particle size distribution, molecular weight distribution, polymer particle nucleation rates, rates of polymerization, and so on. In this work styrene polymerizations are carried out in suspension and emulsion processes simultaneously. The initial reactor charge resembles the recipe of standard styrene suspension polymerizations, while emulsion polymerization constituents are added during the batch. The influence of the moment when emulsion feed is started on the course of the polymerization and the effects on the polymer properties are analyzed. A mathematical model is developed to describe the behavior of the system. Simulation data obtained with the proposed model are in good agreement with experimental conversion, average molecular weight and molecular weight distribution data. It was observed that the polymer particle morphology and the average molecular weight change very significantly with the emulsion feed time and that such changes can lead to bimodal molecular weight distributions. Core-shell polymer particles were obtained, with the core being formed by polymer particles from the suspension polymerization process and the shell formed by polymer particles from the emulsion one.
Modeling; core-shell; simultaneous polymerization; semi-batch
