A flame retardant containing biomass-based polydopamine for high-performance rigid polyurethane foam

The application safety of rigid polyurethane foam (RPUF) is greatly restricted by its flammable characteristics, and the existing inorganic flame retardants have dispersibility and compatibility problems with organic matrices. Taking advantage of the good coating performance and chemical structure of biomass polydopamine (PDA), an inorganic additive flame retardant aluminium hydroxide (ATH) with biomass surface modification was prepared. The effects of unmodified and silane coupling agent modified flame retardants on the thermal, mechanical, and flame retardant properties of RPUF were compared. The study found that the overall performance of the composite material was maximized by PDA by enhancing the interaction between ATH and the matrix. Compared with RPUF and RPUF/ATH, the compressive strength of RPUF/ATH@PDA increased by 3.4% and 10.0%, respectively, and the ultimate flexural strength surged by 26.5% and 30.3%. Compared with RPUF and RPUF/ATH, the addition of ATH@PDA reduced the peak heat release rate of RPUF composites by 39.9% and 24.9%, and the total heat release by 33.6% and 31.9%. In addition, PDA promoted the conversion of RPUF to a dense and highly graphitized carbon residue during combustion and reduced the flammable and harmful gases in the combustion gas. It played a crucial role in the condensed and gas phases, which minimized the fire hazard of RPUF.