In-situ packing self-intumescent aerogel particles in rigid polyurethane foam towards thermal insulation, flame retardance and smoke suppression

Rigid polyurethane foam (RPUF), a commonly employed thermal insulation material in buildings, is highly flammable, however, incorporating flame-retardant additives or fillers is significantly limited by their incompatibility, low effectiveness and negative impact on thermal insulation properties. Herein, a novel and simple interfacial bonding and in-situ packing strategy has been proposed to introduce self-intumescent biomass aerogel particles into RPUF. The result aerogel/RPUF composite manifested continuous and "sea-island" pore structures with a firm bonding interface between aerogel and RPUF due to the highly reactive activity between biomass chains (amino and hydroxyl groups) and isocyanate. Benefitting from the intricate thermal conductive paths and enhanced interface resistance, introducing aerogel particles can reduce the thermal conductivity from 36.5 mW center dot m- 1 center dot K- 1 (RPUF) to 28.6 mW center dot m- 1 center dot K- 1, dropped by 21.6 %. Moreover, the aerogel/RPUF composite manifested excellent flame retardancy with a limiting oxygen index of 28 %, a significantly reduced peak heat release rate (-38.0 %) and smoke production (-54.0 %), as well as enhanced compressive strength (+93.7 %). This work provided new insight into fabricating RPUF composites with integrated advantages of high flame-retardant efficiency and outstanding thermal insulation.