Impregnation of phytic acid into the delignified wood to realize excellent flame retardant

Introducing bio-based acid sources into the cellulose lumens is an effective way to enhance the flame retardant of wooden products. The wood was delignified at first and then phytic acid (PA) was adsorbed solely into the vessels of the wood. With only 8.0 wt% addition of PA, the highly flame retardant wood was obtained. The limiting oxygen index (LOI) of the treated sample was reached 37.2%, the sample also passed the V-0 grade in the UL-94 vertical burning test, and in the CONE test, the total heat release was reduced by 71.3% compared to that of the Natural wood sample. The flame retardant mechanism was probed and summarized as capture of the flaming radicals, the synergistic promotion on charring and suppression on heat and smoke release. After hot-pressing, the flame-retardant treated wood sample exhibited much enhanced mechanical properties, its tensile strength went up to 138 MPa and its bending strength reached 213 MPa, which are 6 times and 7.8 times higher than that of the Natural wood, respectively. This work provided a simple and environmental-friendly method to prepare flame retardant wood for furniture applications.