1. Fabric burning mechanism
(1) The combustion phenomenon can be divided into two types: flammable combustion and flameless combustion. The former is the combustion of the gas or volatile liquid formed during the thermal cracking of the fiber, and the latter is the oxidation of the residue (carbon).
(2) The combustion of fiber is related to its thermal cracking products, and the thermal cracking process of different fibers is different.

2. Flame Retardant Mechanism
(1) Covering theory: flame retardants can form an insulating covering layer on the surface of the fiber at >500 ℃, which not only hinders the supply of O2, but also prevents the outward diffusion of combustible gases, so as to achieve the purpose of flame retardant, such as borax-boric acid .
(2) Gas theory:
One is that the flame retardant decomposes incombustible gas at the combustion temperature, and the concentration of the flammable gas is diluted below the concentration that can generate a flame; the other is that the flame retardant can be used as a highly reactive free radical transfer under heating conditions. form, thereby preventing the free radical reaction from proceeding.
(3) Thermal theory:
One is that the flame retardant undergoes endothermic changes at high temperature, such as melting and sublimation, thereby preventing the spread of combustion, and the other is that the fiber rapidly dissipates heat, so that the fabric cannot reach the combustion temperature.
(5) Catalytic dehydration theory
Mainly refers to changing the thermal cracking process of fiber. Because the flame retardant can make the cellulose molecular chain undergo rapid and massive dehydration before breaking, and even some cross-linking effect, prevent the formation of L-glucose, and inhibit the flaming combustion.
The flame retardant effect of organophosphorus compounds is that it can form esters with hydroxyl groups in cellulose molecules, prevent the formation of L-glucose, and further dehydrate cellulose, generate unsaturated double bonds, and promote the formation of cross-links between cellulose molecules. The formation of carbon-like substances has better smoldering effect. Only when the amount of finishing agent is increased to 10%, can flame burning be effectively prevented.