A novel phosphorus-modified silica aerogel for simultaneously improvement of flame retardancy, mechanical and thermal insulation properties in rigid polyurethane foam

Due to the wide application of rigid polyurethane foam (RPUF) in the fields of building structural materials and thermal insulation materials, the development of high-performance RPUF composites with exceptional flame retardancy, smoke suppression, and mechanical properties is of paramount importance. In this study, we present an approach involving the amalgamation of a phosphorus-containing diol with ammonium polyphosphate to fabricate phosphorus-hybridized silica aerogel (P-SiA). The unique dual hydroxyl configuration of DDP exhibits a remarkable reactivity with silica sol, thereby facilitating the effective dispersion of APP within the silica sol. Additionally, the polyhydroxyl structure within the P-SiA enhance its compatibility with the RPUF. The compressive strength of RPUF/P-SiA-5 increased by approximately 46.4% in comparison to pristine RPUF. Furthermore, in contrast to pristine RPUF, the thermal insulation effect of RPUF/P-SiA composites were further enhanced. In addition, the effective integration of two distinct phosphorus-containing compounds in P-SiA effectively enhances the flame retardancy of RPUF composites, as substantiated by the achievement of a limiting oxygen index value of 23.2% for RPUF/P-SiA-15. Besides, relative to RPUF containing pure silica aerogel, both heat release and smoke release of RPUF/P-SiA composites are effectively suppressed. The implications of these findings propose a new strategy of tailoring material interactions and optimizing composite formulations to obtain the high-performance RPUF composites, which has a broad application prospect.