Synergistic effect of silica aerogels and hollow glass microspheres on microstructure and thermal properties of rigid polyurethane foam

Insulation materials with excellent thermal properties are pivotal components for the next-generation green building materials. In this study, several novel rigid polyurethane foam (RPUF) composites modified by silica aerogels and hollow glass microspheres (HGMs) were prepared. The microstructure, mechanical, physical and thermal properties of the specimens were characterized. The results showed that the addition of fillers changed the microstructure of RPUF. Furthermore, the thermal conductivity of rigid polyurethane foam filled with silica aerogels and HGMs (PUAH) decreased from 24.4 to 22.7 mW/mK, and the compressive strength of PUAH was 51.1% higher than that of pure RPUF. Thermogravimetric analysis (TGA) exhibited that the thermal stability of PUAH was improved, which was evidenced by the delayed thermal decomposition temperature. Notably, the results of cone calorimeter test (CCT) demonstrated that, compared with pure RPUF, the total heat release (THR) and total smoke production (TSP) of PUAH decreased by 23.2% and 21.6%, respectively. The above results proved that there was a synergistic effect of silica aerogels and HGMs in enhancing the various performance of RPUF composites.