The characteristics of flame retardants are generally: it can not burn (this is the most important), and the melting point is very high. For example, MgO can't burn (MG is the highest valence state and can't be oxidized), and the melting point is high (ionic crystal with high lattice energy). Because it can't burn, it doesn't support combustion. Because of its high melting point, it is more likely to keep its original form at high temperature to play a protective role. In addition, dense flame retardants are more likely to play a protective role. In addition, some flame retardants can absorb heat through endothermic reaction to reduce the degree of combustion, and can extinguish the flame by releasing non combustion supporting gas.


In fact, there are many kinds of flame retardants. The above only explains some common principles of action. In many cases, specific analysis should be made according to the effective components of specific flame retardants.