Modelling of the High-Impact Polystyrene Morphogenesis

Summary: High-impact polystyrene (HIPS) is a hetero-phase polymer with the so-called salami morphology. Salami morphology is formed by a continuous PS phase containing micron-sized PB domains. PB domains contain submicron-sized irregular PS occlusions. In our modeling work we addressed several weak points of Cahn-Hilliard model of HIPS salami morphology evolution. The weakest point of Cahn-Hilliard model is the inherently present Ostwald ripening destabilizing or competing with graft-stabilized domains. Two mechanism of formation of HIPS morphology are supported by the model: (i) encapsulation of graft-stabilized PS-rich domains in PB particles, and (ii) polymerization of styrene dissolved in PB-rich phase and subsequent phase separation leading to PS occlusions in PB domains.