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The mechanism of flame retardant ?

Feb 21, 2019

The flame retardant reaction of the polymer is a complicated process. The gas phase and the solid phase coexist, and the organic reaction and the inorganic reaction proceed simultaneously. At high temperatures, many small molecular substances and macromolecular substances are produced and changed.

General combustion must have three conditions: 1 with flammable substances; 2 with temperature reaching the ignition point; 3 with sufficient oxygen. As long as one of them is missing, the fire is extinguished. Flame retardant is one or several factors used in the community. , flame retardant can be carried out through the following ways.

(1) The endothermic reaction occurs on the surface to produce a cooling effect

The flame retardant may undergo endothermic decomposition or endothermic reaction with the substrate to lower the temperature below the temperature required for the flame to maintain its own chain reaction; or the free radicals or molecules generated by the decomposition of the flame retardant can be present in the flame. The substance acts as an endothermic reaction, thereby interfering with the heat balance of the combustion.

(2) Producing non-combustible gases

On the one hand, the incombustible gas can remove oxygen from the surface of the polymer; on the other hand, the flammable gas is diluted, and the decomposition combustion is carried out in the direction of generating incombustible gas.

(3) Carbonized layer on the surface

The carbonized layer produced on the surface can block air, heat, etc., preventing the flammable substance from interfering with oxygen, and at the same time, the polymer can not get enough heat to decompose, and the speed of "fuel" is reduced.

(4) Inhibition of flammable gas products

Since phosphate and the like promote carbonization, the generation of flammable gases is suppressed.

(5) Cut off the chain reaction

Since HO• plays an important role in combustion, the addition of substances capable of decomposing free radicals can remove HO• and interfere with the chain reaction in the flame to stop the combustion.

(6) Producing a gas with a relatively high density

Gas with relatively high density can hinder the exchange of combustion gases with air.