How to realize flame retardant modification of the

2022-08-07
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How to realize flame retardant modification of modified plastics

the application of modified plastics in home appliances, electronic appliances, automobiles and other fields often requires flame retardancy, and flame retardancy modification can be achieved by adding flame retardants. There are bromine flame retardant and halogen-free flame retardant

flame retardant

flame retardant, also known as fire retardant, fire retardant or fire retardant, is a functional additive that gives the flammability of flammable polymers. Most of them are compounds of group Ⅴ a (phosphorus), Ⅶ a (bromine, chlorine) and Ⅲ a (antimony, aluminum) elements in the periodic table

flame retardant principle of modified plastics

I. endothermic effect

the heat released by any combustion in a short time is limited. If part of the heat released by the fire source can be absorbed in a short time, the flame temperature will be reduced, the heat radiated to the combustion surface and acting on the cracking of vaporized combustible molecules into free radicals will be reduced, and the combustion reaction will be restrained to a certain extent

under high temperature, the flame retardant has a strong endothermic reaction, absorbs part of the heat released by combustion, reduces the surface temperature of combustibles, effectively inhibits the generation of combustible gases and prevents the spread of combustion

II. Covering effect

after adding flame retardant to combustible materials, the flame retardant can form glassy or stable foam to cover 7.3 batch layers at high temperature, isolate oxygen, have the functions of heat insulation, oxygen isolation and preventing combustible gas from escaping outward, so as to achieve the purpose of flame retardance

for example, organic phosphorus inhibiting flame retardants can produce crosslinked solid substances or carbonized layers with more stable structure when heated. On the one hand, the formation of the carbonized layer can prevent the further pyrolysis of the polymer, on the other hand, it can prevent the internal thermal decomposition products from entering the gas-phase synthesis mode to participate in the combustion process

III. inhibition of chain reaction

according to the chain reaction theory of combustion, free radicals are required to maintain combustion. The flame retardant can act on the gas-phase combustion zone to capture the free radicals in the combustion reaction, so as to prevent the spread of the flame, reduce the flame density in the combustion zone, and finally reduce the combustion reaction speed until termination

IV. asphyxiation of incombustible gas

when the flame retardant is heated, it decomposes incombustible gas, diluting the concentration of the combustible gas decomposed from the combustible to below the lower limit of combustion. At the same time, it can also dilute the oxygen concentration in the combustion area. Whether there is leakage at the water channel and gas pipe connector, so as to prevent the continuation of combustion and achieve the flame retardant effect

plastic flame retardant grade

flammability UL94 grade is the most widely used flammability standard for plastic materials. It is used to evaluate the ability of materials to extinguish after being ignited. According to the burning speed, burning time, anti dripping ability and whether the droplet burns, there are many evaluation methods

flame retardant grade of Plastics: from Hb, V-2, V-1, V-0, 5vb to 5VA. HB: the lowest flame retardant grade in UL94 standard

flame retardant compounding technology is also developed with flame retardant. Flame retardant compounding technology refers to compounding among phosphorus, halogen, nitrogen and inorganic flame retardants, or within a certain type of flame retardant. In the practical application of flame retardants, a single flame retardant often has some defects, which is difficult to meet people's higher and higher requirements. Therefore, through the flame retardant compounding technology, we can integrate the advantages of two or more flame retardants, learn from each other, and maximize the synergistic effect of flame retardants, so as to reduce the dosage and enhance the flame retardant effect

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