1、Flame retardant - cooling effect

　　Some flame retardants can absorb the heat released by the plastic when burning, so that the temperature of the burning plastic drops, preventing it from continuing to degrade or cracking, interrupting the source of combustible gas, so that the flame is extinguished, such as organic phosphorus nitrogen expansion type flame retardant; for example, borax has 10 molecules of crystalline water, as the release of crystalline water to seize 141.8kJ/mol heat, due to its heat absorption and the temperature rise of the material is The flame retardant effect is thus suppressed due to its heat absorption. The flame retardant effect of alumina hydrate is also due to the heat absorbing effect of heat dehydration. In addition, some thermoplastic polymers often produce molten droplets when cracking, because they can leave the combustion area to remove the reaction heat, can also play a certain flame retardant effect.

　2、Smoke suppression - isolation effect

　　In the combustion process to produce non-combustible gas or foam layer, or the formation of a liquid or solid cover layer, so that the combustion process is suspended due to the absence of oxygen supplement, such as halogen flame retardants, expanded graphite and polyol and polyvinyl alcohol.

　　The covering effect is to generate a stable covering layer at higher temperatures, or to decompose and generate foam-like substances to cover the surface of polymer materials, making it difficult for the heat generated by combustion to enter the interior of the material, making it difficult for the combustible gases generated by the thermal decomposition of polymer materials to escape, and acting as an air barrier to the material, thus inhibiting the cracking of the material and achieving the effect of flame retardancy. Such as phosphate ester compounds and fireproof foam coatings can play a role according to this mechanism.

　　3. Heat dissipation - elimination of free radicals

　　In the combustion process, it can eliminate the free radicals O- and OH- generated by cracking or pyrolysis, so that the middle of the chain reaction of combustion, cutting off the source of combustible gases, such as halogen flame retardants. Some substances can capture the active intermediates of the combustion reaction, such as HO-, H-, -O- and HOO-, to inhibit the free radical chain reaction and reduce the burning rate until the flame is extinguished. Commonly used bromine, chlorine and other organic halogen compounds have this inhibitory effect.

　　4, anti-drop - dilution effect

　　In combustion can release inert gas, dilute the concentration of combustible gases and oxygen in the combustion area, so that combustion can not be carried out, such as boron compounds and molybdenum compounds.

　　Such substances can produce a large amount of non-combustible gas when decomposed by heat, so that the combustible gas produced by the polymer material and the oxygen in the air is diluted and does not reach the concentration range of combustible, thus preventing the polymer material from igniting and burning. Some of the gases that can be used as diluting gases are CO2, NH3, HCl and H2O. Amine phosphate, amine chloride, amine carbonate etc. produce this non-flammable gas when heated.