P- N synergies for wood fire safety

Bio-based PIN FRs, APP and melamine derivative improved fire safety of wood. Bio-based PIN FRs (sodium lignosulfonate and chitosan) were used with ammonium polyphosphate (APP) at 1% - 3% in a melamine-modified urea-formaldehyde resin, applied as a 0.3 mm coating to wood. UL94, LOI and cone calorimeter were used to evaluate fire performance. Compared to untreated wood, peak heat release rate was reduced by nearly -80% and carbon monoxide emission was reduced by two thirds. Analysis showed that the PIN FR coating caused the formation of a dense char layer in fire. The authors conclude that the effectiveness of the PIN FR combination is due to synergy between nitrogen (chitosan, melamine-derivative), phosphorus and lignin-based compounds.

“A Phosphorus–Nitrogen Synergistic Flame Retardant System for Wood Coatings: Enhanced Fire Resistance and Smoke Suppression”, M. Lv et al., ChemistrySelect , 2026, 11:e05212, https://doi.org/10.1002/slct.202505212