Effect of nitrogen phosphorus flame retardants on thermal degradation of wood

The effects of flame retardant action of wood treated with flame retardants that were obtained from phosphorus acid, pentaerythritol, urea, and triethanolamine through copolycondensation were studied in this research. Flame retardancy was characterized by limiting oxygen index (LOI), and the Broido method was used to evaluate the kinetics of thermal decomposition on untreated and treated wood. The effectiveness of these flame retardants was also investigated using scanning electron microscope (SEM) images of char formed after LOI tests. The results showed that adding the flame retardant decreases the thermal activation energy at a high degree of degradation, leading to the increase of LOI values. SEM images of chars showed the formation of protective polymeric coatings on char surfaces, and such coatings protected the substrate from damaging, resulting the integrity of wood fiber morphology and improvement of flame retardancy of wood during burning process.