蜜桃久久精品成人无码AV_国产成A人片在线观看视频下载_国内精品久久久久精品爽爽_国产乱子伦

The application of modified plastics in home appliances, electronic appliances, automobiles and other fields often requires flame retardance, and flame retardancy modification can be achieved by adding flame retardants. Do you know the 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 conditions, 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. Coverage. After the flame retardant is added to the combustible materials, the flame retardant can form a glass like or stable foam covering layer at high temperature, isolate oxygen, have the functions of heat insulation, oxygen isolation and preventing the escape of combustible gases, so as to achieve the purpose of flame retardance. For example, when heated, organic phosphorus inhibitor flame retardants can produce crosslinked solid substances or carbonized layers with more stable structure. 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 to participate in the combustion process.

III. inhibition of chain reaction. According to the chain reaction theory of combustion, free radicals are needed 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 reduce the combustion reaction speed until termination.

IV. asphyxiation effect of non combustible gas. When the flame retardant is heated, it decomposes into non combustible gas, and dilutes the concentration of combustible gas decomposed from combustibles below the lower limit of combustion. At the same time, it can also dilute the oxygen concentration in the combustion zone, prevent the continuation of combustion and achieve the effect of flame retardance.

Source: Jiangmen engineering plastics http://www.fcyou.com/