Construction of a Phytic Acid–Silica System in Wood for Highly Efficient Flame Retardancy and Smoke Suppression

Abstract

The intrinsic flammability of wood restricts its application in various fields. In this study, we constructed a phytic acid (PA)–silica hybrid system in wood by a vacuum-pressure impregnation process to improve its flame retardancy and smoke suppression. The system was derived from a simple mixture of PA and silica sol. Fourier transform infrared spectroscopy (FTIR) indicated an incorporation of the PA molecules into the silica network. Thermogravimetric (TG) analysis showed that the system greatly enhanced the char yield of wood from 1.5% to 32.1% (in air) and the thermal degradation rates were decreased. The limiting oxygen index (LOI) of the PA/silica-nanosol-treated wood was 47.3%. Cone calorimetry test (CCT) was conducted, which revealed large reductions in the heat release rate and smoke production rate. The appearance of the second heat release peak was delayed, indicating the enhanced thermal stability of the char residue. The mechanism underlying flame retardancy was analyzed by field-emission scanning electron microscope coupled with energy-dispersive spectroscopy (SEM-EDS), FTIR, and TG-FTIR. The improved flame retardancy and smoke-suppression property of the wood are mainly attributed to the formation of an intact and coherent char residue with crosslinked structures, which can protect against the transfer of heat and mass (flammable gases, smoke) during burning. Moreover, the hybrid system did not significantly alter the mechanical properties of wood, such as compressive strength and hardness. This approach can be extended to fabricate other phosphorus and silicon materials for enhancing the fire safety of wood.

Study on properties of gelatin–silica mineralized wood composite

“…Lignin will be carbonized at 380–500°C, and the formation of a charcoal layer reduces the loss of wood quality. [ 20,21 ]…”

“…Lignin will be carbonized at 380-500 C, and the formation of a charcoal layer reduces the loss of wood quality. [20,21] Based on the TGA curve depicted Figure 8 and TGA data presented in Table 1, the mass losses associate with untreated wood and TEOS-impregnated modified wood after pyrolysis reached 88% and 76%, respectively, and the minimum mass loss associated with mineralized wood was 67%, indicating that gelatin synergistic silica can promote the formation of the carbon layer. Based on the DTG curve depicted in Figure 8 and data presented Table 1.…”

Research and Application of Biomass-Based Wood Flame Retardants: A Review

“…Chen et al [ 85 ] constructed a phytic acid (PA)-silica hybrid system in wood by vacuum pressure impregnation to improve its flame retardancy and smoke suppression. The improvement in the flame-retardant and smoke-suppressing properties of wood is that the char residues form a completely coherent and cross-linked structure.…”

Preparation of multifunctional flame retardant composite wood by doping poplar cell walls with metal phytates

“…In the gas phase, PA decomposes PO• and HPO radicals to trap H• and OH•, thus terminating the chain reaction and achieving ame retardancy. Therefore, PA has excellent ame retardant potential and is rapidly becoming a research hotspot for the implementation of sustainable development strategies (Chen et al 2021;Bloot et al 2023). The ame retardant e cacy of PA-based ame retardants has now been demonstrated in many materials, including cotton fabrics, polymers and wood (Liu et The poor hygroscopicity and smoke suppression of wood impregnated with PA limits its use.…”