ABSTRACT The development of environmentally friendly and effective flame retardants is critical for improving the fire safety of wood materials. In this study, a bio‐based flame retardant system composed of sodium lignosulfonate, chitosan, and ammonium polyphosphate was incorporated into a melamine‐modified urea–formaldehyde resin to enhance the flame retardancy of wood surfaces. Combustion behavior was evaluated using cone calorimetry. Compared to untreated wood, the treated samples exhibited a 78.89% reduction in peak heat release rate, a 68.68% decrease in total heat release, and a 75.32% reduction in the flame growth index. The synergistic action of carbon‐, nitrogen‐, and phosphorus‐containing components promoted the formation of a dense char layer, effectively suppressing oxygen ingress and heat release during combustion. This work demonstrates a sustainable and efficient strategy for improving the thermal stability and fire resistance of wood via resin‐based surface modification and offers theoretical insights for the design of high‐performance flame retardant coatings.
Lv et al. (2026) studied this question.