1. Non-combustible means that the substance itself cannot be burned, and flame-retardant means that it has no burning ability or is not easy to burn.
2. Flame retardant can sometimes be close to or in contact with fire sources, such as asbestos flame retardant, and gasoline needs to be fire resistant. Flame retardant can also be understood as fire resistance, which is different from non-combustible. Non-combustible means that the substance is non-combustible, not non-combustible.
3. Not all flame retardant materials are combustible and combustible materials. Flame retardants are mainly organic and inorganic, halogen and non-halogen. Organic is some flame retardants represented by bromine, nitrogen, red phosphorus and compounds. Inorganic are mainly antimony trioxide, magnesium hydroxide, aluminum hydroxide, silicon and other flame retardant systems.
1. Flame-retardant reaction mechanism of polymer materials
1. Endothermic effect The heat released during the combustion process heats the raw material, making it quickly reach the ignition point. The principle of endothermic flame retardancy is that the material needs to absorb a large amount of heat during the combustion process, which can reduce the heating process of the material. It is difficult for the free radicals cracked by the converted combustible molecules to reach the ignition point, which inhibits the progress of combustion to a certain extent.
2. The high temperature generated when the covering material burns makes the flame retardant form a glassy or stable foam covering layer to isolate oxygen, so that it not only insulates and insulates oxygen, but also prevents the escape of combustible gas, so as to achieve the purpose of flame retardancy.
3. Inhibition of chain reaction According to the chain reaction theory of combustion, free radicals are needed to maintain combustion. Flame retardants can act on the gas phase combustion zone to capture free radicals in the combustion reaction, thereby preventing the spread of flames, reducing the flame density in the combustion zone, and ultimately reducing the combustion reaction speed until it stops.
4. Non-combustible gas suffocation The flame retardant decomposes non-combustible gas when heated, and dilutes the concentration of combustible gas from combustibles to below the lower combustion limit. At the same time, it also dilutes the oxygen concentration in the combustion zone, prevents the combustion from continuing, and achieves the effect of flame retardancy.
2. How to choose flame retardant
There are many types of flame retardants, and their flame retardant effects are also different. Different polymer materials choose different flame retardants, but the basic requirements are the same.
1. High flame retardant efficiency and high efficiency/price ratio;
2. The ecological and environmental protection requirements are strict, so the following ecological and environmental protection characteristics should be possessed:
(1) Harmless to humans, animals and plants;
(2) Difficult to migrate;
(3) The amount of toxic and corrosive gases (including smoke and dust) released during thermal cracking or combustion should be less;
(4) It is easy to recycle and does not deteriorate or slightly deteriorate the performance of mechanical recycling products;
(5) Compatible with the environment.
3. Good compatibility with the flame-retardant substrate;
4. Good thermal stability, good decomposition temperature is between 250℃~400℃;
5. Little influence on the processing performance and physical and mechanical properties of the flame-retardant substrate;
6. Has a certain light stability;
7. The source of raw materials is sufficient, and the price can be accepted by downstream users. An ideal flame retardant can meet the above conditions at the same time, but it is almost impossible in fact. Therefore, when choosing a practical flame retardant, most of them are based on the premise of meeting the basic requirements and compromise among other requirements. Good overall balance.
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