Mechanism of flame retardant?

Mechanism of flame retardant?

Flame retardants exert their flame retardant effects through several mechanisms, such as endothermic effect, covering effect, inhibition of chain reaction, asphyxia of non-combustible gas, etc.Most flame retardants achieve the purpose of flame retardant through the combined action of several mechanisms.

1. Endothermic effect

Any heat released by burning in a relatively short time is limited, if you can in a relatively short time to absorb part of the fire produced by heat, the flame temperature will reduce, and ACTS on the surface will have radiation to the gasification of combustible molecules into free radicals can reduce quantity of heat, combustion reaction will be a certain degree of inhibition.Under the condition of high temperature, the flame retardant has a strong endothermic reaction, absorbs part of the heat released by combustion, reduces the surface temperature of combustible, effectively inhibits the formation of combustible gas, and prevents the spread of combustion.The flame retardant mechanism of Al(OH)3 flame retardant is to increase the heat capacity of the polymer, so that it can absorb more heat before reaching the thermal decomposition temperature, so as to improve its flame retardant performance.This kind of flame retardant gives full play to its heat absorption characteristics when combined with water vapor and improves its own flame retardant ability.

After adding flame retardant in combustible material, flame retardant can form glassy or stable foam covering layer at high temperature, isolate oxygen, have heat insulation, oxygen isolation, prevent combustible gas to escape out of the role, so as to achieve the purpose of flame retardant.For example, when the organophosphorus flame retardants are heated, they can produce a more stable structure of cross-linked solid substances or carbonized layers.On the one hand, the formation of the carbonization layer can prevent the further pyrolysis of the polymer, and on the other hand, it can prevent the internal thermal decomposition products from entering the gas phase to participate in the combustion process.

According to the chain reaction theory of combustion, what is needed to sustain combustion is free radicals.The flame retardant can act on the gas phase combustion zone, capture the free radicals in the combustion reaction, thus preventing the spread of flame, reducing the flame density in the combustion zone, and finally reducing the combustion reaction speed until the termination.For example, the evaporation temperature of halogenated flame retardant is the same or close to the decomposition temperature of polymer. When the polymer is decomposed by heat, the flame retardant also volatilizes out.At this point, the halogenated flame retardant and the thermal decomposition products are in the gas phase combustion zone at the same time, and the halogen can capture the free radicals in the combustion reaction and interfere with the combustion chain reaction.

Amber Zhang Ms.

Foreign trade 

Zhejiang Ruico Advanced Materials Co., Ltd. (Stock No.873233)

Add: No.188, Liangshan Road, Linghu Town, Nanxun District, Huzhou City, Zhejiang Province, China 313018

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