PIN flame retardants were effective for fire safety of wood – polyethylene composites, remaining effective after weathering. Addition of wood flour to polyethylene (PE) increases mechanical performance and also reduces flammability for uses such as exterior decking and siding. Analysis of previous studies showed that ammonium polyphosphate (APP) and magnesium hydroxide (MDH) were effective flame retardants when compounded into the PE – wood particles blend (35% polyethylene, 50% wood fibre, 10% flame retardant compared to control 35% / 60% / zero FR). 60% wood reduced peak heat release rate by 76% compared to neat polyethylene, and 50% wood – 10% MDH by 84%. MDH and APP were identified as the most effective flame retardants for the polymer – wood composite tested, compared to a brominated FR, with limited impact of weathering.
“Durability and performance of wood flour/polyethylene composites containing fire retardants after weathering via ASTM D2565”, M. Dietenberger et al., J. Fire Sciences 2024 https://doi.org/10.1177/07349041241237536