The Polyurethane-Polystyrene Composite—Influence of the Blowing Agent Type on the Foaming Process, the Structure and the Properties

In this study, polyurethane-polystyrene composites (RPURF-EPS) were obtained with the co-expansion method. This method consists of utilizing the heat of the exothermic reaction of polyurethane (PUR) formation to expand polystyrene beads (PSBs). The materials were obtained using polyurethane systems based on the selected blowing agents, such as cyclopentane, a mixture of fluorocarbons and water. The analysis of the foaming process was carried out using a special device called FOAMAT. The characteristic start, rise, gelation and curing times were defined. The rise profile, the reaction temperature, the pressure and the dielectric polarization were measured. The influence of selected blowing agents on the cell structure and physical–mechanical properties of reference rigid polyurethane foam (RPURF) and RPURF-EPS, such as apparent density, compressive strength and thermal conductivity, were evaluated. Based on the research, the blowing agents that have the most beneficial influence on the properties and structure of the composites and that provide the most efficient expansion of PSBs in a light porous composite were found.