Thermal analysis and kinetics of larch treated by phosphorus-amine-formaldehyde flame retardants

Larch was treated with phosphorus-amine-formaldehyde flame retardants. The thermal degradation of the treated larch samples was studied by thermal analysis and cone calorimeter. The flame retardant properties were characterized in limiting oxygen index, char yield, heat release rate and total heat release. Kinetic parameters of thermal degradation were obtained following the method of Broido. The limiting oxygen index and char yield increased while the heat release rate and total heat release decreased, which shows that combustibility of larch has largely decreased. For the degradation of the larch treated with flame retardants, the activation energy was greatly decreased, which shows that the flame retardants catalyze the dehydration and decomposition of larch. The main decomposition of larch occurred at lower temperatures (<300°C) through the reaction which includes dehydration, rearrangement, carbonization, evolution of carbon monoxide and carbon dioxide, and ultimately a carbonaceous residue, resulting in the formation of less flammable products and correspondingly more char, leading to low combustibility.