Flame retardant properties of MIL-100 (Fe) treated poplar wood

Objective In order to improve the flame retardant and smoke suppression performance of wood, metal organic framework material (MOF) was used as a new flame retardant and MIL-100(Fe) was used to treat wood to prepare a green and environmentally friendly flame retardant material, aiming to provide a new idea for wood flame retardant.

Method Using MIL-100(Fe) as flame retardant, MIL-100(Fe) was synthesized in situ in wood by atmospheric pressure immersion (W-JP group) and vacuum immersion (W-JZ group). Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to analyze the morphology and structure of MIL-100 (Fe) treated wood. Nitrogen adsorption method was used to characterize the pore structure of MIL-100 (Fe) treated wood. The limiting oxygen index, thermogravimetric test and cone calorimetry test were used to evaluate the thermal stability and flame retardant and smoke suppression performance of MIL-100 (Fe) treated wood. Finally, SEM and FTIR were used to characterize the morphology and structure of the carbon residue and analyze the mechanism.

Result MIL-100(Fe) could be synthesized in situ in wood by both treatment methods, and more MIL-100(Fe) precursor solution in the W-JZ group entered the wood and crystallized with a mass gain rate of 24.36%, resulting in a more complete and uniform crystal structure and smaller size. MIL-100 (Fe) treated wood showed good thermal stability, and the carbon residue rate of the W-JZ group increased by 39.99% and the peak thermal mass loss rate decreased by 26.47%. The total heat release and total smoke release of MIL-100 (Fe) treated wood were reduced, and the flame retardant and smoke suppression performance was good. MIL-100(Fe) exerted the synergistic effect of gas phase and condensed phase flame retardant. In the process of decomposition, it released non-combustible gases to dilute the concentration of combustible gases, and at the same time adsorbed the smoke by utilizing the multi-stage pore structure. The Fe₃O₄ formed after decomposition catalyzed the dehydration reaction of wood to form a dense charcoal layer, which prevented the transfer of heat and oxygen and the release of flammable volatile products.

Conclusion In this study, MIL-100 (Fe) treated wood is successfully prepared by in-situ synthesis method, which effectively improves the thermal stability and flame retardant and smoke suppression properties of wood, and enriches the existing wood flame retardant system.