The mechanism of flame retardant fabric
1. Principle of fabric combustion performance.
(1) combustion can be divided into two types: flame combustion and non-flame combustion. The former is the combustion of the gas or volatile liquid formed during the thermal cracking of the fiber, while the latter is the oxidation of the residue (carbon).
(2) the combustion of the fibers is related to the product of pyrolysis, and the pyrolysis process of different fibers is different.
2. Mechanism of flame retardant:
(1) covering theory of flame retardants in > 500 ℃ in the fiber surface form a blanket has isolation effect, in addition to hinder the supply of O2, also prevent flammable gas spread outward, so as to achieve purpose of flame retardant, such as borax and boric acid.
(2) gas theory: first, the flame retardant can decompose the non-flammable gas at the combustion temperature, and dilute the flammable gas concentration to produce the flame concentration below; The other is that the flame retardant can be used as a high activity base transfer in the heating condition, thus preventing the free radical reaction.
(3) heat theory: the first is that the flame retardant changes at high temperature, such as melting and sublimation, thus preventing the burning and spreading; The other is the rapid heat dissipation of the fibers, making the fabric less than the burning temperature.
(4) catalytic dehydration theory: mainly refers to the process of pyrolysis of fiber. Because the flame retardant can cause the cellulose molecular chain to undergo rapid and massive dehydration before the rupture, even some cross-linking effect can prevent the formation of left-lateral glucose and inhibit the flame combustion.
Flame retardant effect of organophosphorus compounds is because it can and hydroxyl of the cellulose molecules form ester, prevent the formation of glucose left-handed, dehydration, and further make cellulose generated unsaturated double bond, promote the cellulose molecules formed between crosslinking, increase the formation of the carbon material, flame resistance effect is better. Only when the amount of finishing agent is increased to 10% can the flame be effectively prevented.Apparatus for flame retardant testing of fabrics: limit oxygen index tester, horizontal combustion tester, thermal protective clothing tester, and vertical combustion tester.
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