Covering effect of flame retardants

After adding flame retardants to combustible materials, flame retardants can form glassy or stable foam covering at high temperatures, isolate oxygen, and have the effect of heat insulation, oxygen insulation, and preventing combustible gas from escaping outward, so as to achieve the purpose of flame retardancy. For example, organophosphorus flame retardants can produce cross-linked solid substances or carbide layers with a more stable structure when heated. On the one hand, the formation of the carbide layer can prevent the polymer from further pyrolysis, and on the other hand, it can prevent the thermal decomposition products inside it from entering the gas phase to participate in the combustion process.