Enhancing flame-retardant and smoke-suppression properties of wooden materials with phytic acid-added composite flame retardants

To enhance the flame-retardant and smoke-suppression of fast-growing wood, Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) was impregnated with environmentally friendly, non-toxic, and green flame retardants and subsequently characterized. The results indicated that compared with unmodified wood, the thermal stability and fire resistance of modified wood were improved, the total heat release of delignification (DWM) and non-delignification (NWM) modified decreased by 47.08 % and 27.87 %, respectively, the total smoke production decreased by 18.24 % and 98.14 %, respectively, and the weight gains of modified wood was significantly increased by 67.12 % and 24.26 %, respectively. The impregnation and filling of composite flame retardants interfered with the crystalline regions of wood and reducing then by 26.86 % and 27.22 %, respectively, but did not change the crystal structure of wood. The appearance of Si-O-C, Si-O-Si, Si-O, Al-O, and P-O characteristic peaks confirmed that the composite flame retardants were not only physically filled but also chemically bound in the wood and formed a gel cross-linked network structure. According to the microscopic morphology observations, the composite flame retardants were uniformly distributed in the wood, and delignification reduced the color difference on the wood surface. Therefore, the composite flame retardant modified wood can be widely used as a decorative material. Simultaneously, this material reduces the possibility of fire, reduces the emission of harmful gases, and enhances environmental protection and human safety.