How do flame retardants act as flame retardants?

How do flame retardants act as flame retardants?
In daily life, flame retardants have very good flame retardant ability, which solves a lot of worries of everyone. How do flame retardants achieve flame retardant effect?
1. Endothermic effect
The amount of calories released by any combustion over a short period of time is limited. If a small fraction of the calories released by the source can be dissolved over a short period of time, the temperature of the flame will be reduced, the number of calories reaching the surface of the combustion and acting on the splitting of the already vaporized combustible molecules into free radicals will be reduced, and the combustion reaction will be forced to stop. It enhances its flame-retardant ability.
2. Covering effect
After adding flame retardant to combustible materials, flame retardant will form glass or stable foam covering layer at high temperature, blocking oxygen, with heat insulation, oxygen insulation, prevent flammable gas from escaping to the effect, so as to achieve flame retardant purpose. For example, when organic phosphorus flame retardants absorb heat, they can form cross-linked solid substances or carbonized layers with more stable structure. The transformation of the carbonized layer can not only prevent the further pyrolysis of the polymer, but also prevent the internal thermal decomposition products from entering the gas phase to participate in the combustion process.