Multi-functional densified wood laminates with hydrophobicity, anti-flammability, and thermal insulation for structural applications

Wood materials have been basic building and structural materials for thousands of years, but because of their particular composition, the flammability and flame retardant modification of wood composites have attracted widespread attention. In this study, a new strategy was designed for flame retardant modification of commercial wood boards, and a series of wood samples were prepared with improved hydrophobic and flame retardant properties via delignification, impregnation of phytic acid (PA) and 3, 5-diamino-1,2,4-triazole (ATA-N), and surface hydrophobic modification of trimethoxymethylsilane. After impregnation with PA and ATA-N, the wood samples exhibited outstanding flame retardant properties, and the Wood@PA/ATA-N sample presented a limit oxygen index (LOI) of more than 80 % and a UL-94 V-0 rating. In addition, the peak heat release rate (PHRR), total heat release (THR) and total smoke production (TSP) of Wood@PA were 92.0 %, 68.0 % and 63.0 % lower than those of the untreated wood. Moreover, surface treatment with organosilane significantly improved the hydrophobicity of the wood surface, and the water contact angle of the surface for Wood@PA/ATA-N/MTMS reached 93.4°, indicating a highly hydrophobicity. In conclusion, the strategies of delignification, flame retardant impregnation and surface modification could significantly improve the flame retardancy and hydrophobic properties of wood samples, thereby increasing their useful life and application value in construction and structural materials.