Porous polyurethane-polystyrene composites produced in a co-expansion process

Abstract Porous polyurethane (PUR) and polystyrene (PS) composites can be obtained by co-expansion process. This method involves simultaneous foaming of PUR and expanding PS beads (PSB), what is possible by utilizing exothermic heat of PUR formation. In this study, PUR-PS porous composites were obtained by using different types of commercial PS beads having various initial sizes. Co-expansion processes were characterized using Foamat device. The following parameters of co-expanded materials were measured: the rise profile, the reaction temperature, the rise pressure and the dielectric polarization. The results analyzes allowed to divide the co-expansion process into 3 stages: PUR foaming below the PS softening temperature, expansion of PUR and PS in the same time, PS expansion after PUR gelling. The addition of PS filler causes: a reduction of the core temperature, increasing the pressure, slowing the PUR reaction formation and the slowdown in the rise velocity of reaction mixture. It also causes the elongation of start, gelling, rise and curing times.