Briefly describe the principle of flame retardant and the flame retardant mechanism of flame retarda

The principle is that the amount of heat emitted by any combustion in a short period of time is limited, and if a part of the heat emitted by the ignition source can be absorbed in a short period of time, then the flame temperature.

It will be lowered, radiating to the burning surface and acting on the cleaved combustible molecules that have been vaporized into free radicals.

The heat will be reduced, and the combustion reaction will be suppressed to a certain extent.

Endothermic. At high temperatures, flame retardants.

A strong endothermic reaction occurs.

Absorbs part of the heat emitted by combustion, lowers the temperature of the surface of combustibles, and effectively suppresses flammable gases.

to stop the spread of burning. The flame retardant mechanism of Al(OH)3 flame retardant is to improve the flame retardant performance by increasing the heat capacity of the polymer so that it can absorb more heat before reaching the thermal decomposition temperature. This type of flame retardant gives full play to its characteristics of absorbing a large amount of heat when combined with water vapor, and improves its own flame retardant ability.

Covering effect. After adding flame retardant to the combustible material, the flame retardant can form a glass-like or stable foam covering layer at high temperature, isolate oxygen, and have the ability to insulate heat, oxygen, and prevent combustible gas.

outward escape, so as to achieve the purpose of flame retardant. For example, organic phosphorus flame retardants can produce cross-linked solid substances or carbonized layers with more stable structures when heated. On the one hand, the formation of the carbonization layer can prevent the polymer from further pyrolysis, and on the other hand, it can prevent the thermal decomposition products inside it from entering the gas phase to participate in the combustion process.

Inhibits chain reaction.

According to the chain reaction theory of combustion, what is needed to sustain combustion are free radicals. Flame retardants can act on the gas-phase combustion zone to capture free radicals in the combustion reaction, thereby preventing the spread of the flame, reducing the flame density in the combustion zone, and finally reducing the combustion reaction speed until termination. For example, halogen-containing flame retardants, its evaporation temperature is the same or similar to the polymer decomposition temperature, and when the polymer is decomposed by heat, the flame retardant also volatilizes at the same time.

At this time, halogen-containing flame retardants and thermal decomposition products are in the gas-phase combustion zone at the same time, halogens.

It can capture the free radicals in the combustion reaction, thereby preventing the spread of the flame, reducing the flame density in the combustion zone, and finally reducing the combustion reaction rate until it is terminated.

Non-flammable gas asphyxiation.

When the flame retardant is heated, it decomposes non-combustible gas, and dilutes the concentration of combustible gas decomposed by combustible materials below the lower combustion limit. At the same time, it also has the effect of diluting the oxygen concentration in the combustion zone, preventing the continuation of combustion and achieving the effect of flame retardant.

The flame retardant principle mainly includes three aspects: gas phase flame retardant, condensed phase flame retardant and carbon layer barrier flame retardant. Different flame retardants play different flame retardant principles, and the compound flame retardants can generally produce three effects of flame retardant.

Flame retardant is a chemical substance widely used in fireproof materials, and its main role is to play a flame retardant role when the material is on fire to avoid the spread of fire. Flame retardants produce a chemical reaction when the material is on fire, and flame retardant is achieved by reducing the temperature generated by the ignition, reducing the supply of oxygen, and generating inert gases.

The flame retardant mechanism of flame retardant is mainly divided into two types: gas phase flame retardant and solid phase flame retardant. Gas-phase flame retardant means that flame retardant can release one or more chemicals with inert gas characteristics when the material is on fire, such as phosphorus, nitrogen, etc., to reduce the contact between combustibles and oxygen, thereby inhibiting the spread of fire. Solid flame retardant means that the flame retardant can form a protective layer when the material is on fire, disperse or absorb the heat energy, reduce its calorific value, and reduce the flue gas and flame intensity generated during the combustion process.

The flame retardant mechanism of flame retardant is one of the core contents of flame retardant technology, and its research aims to improve the flame retardant efficiency and application range of flame retardant. At present, with the continuous development of flame retardant technology, various new flame retardants are gradually emerging, but the core idea of its flame retardant mechanism remains unchanged, that is, chemical substances with inert gas characteristics should be released before or during the ignition process of the material through chemical wax retardant, so as to reduce the supply of oxygen, so as to achieve the effect of flame retardant.

1.Isolate the air (oxygen) gas for combustion conditions. For example, all kinds of fire extinguishers and other products, oil fire sand burial, Qiaohong activated carbon soil covering are made of this principle;

2.Reduce the temperature of combustion. For example, the water used in fire fighting is used to extinguish fires, in order to reduce the high temperature caused by combustion, and to eliminate the evil cycle of ignition and burning.

3.The material itself is not flammable.

The flame retardant here should be smoldering. Smoldering is a form of combustion in solids.

Slow combustion without a flame is known as smoldering, which is commonly found in the combustion of solids, especially solid plastics and other substances, and is the most prone to such reactions, which is a common chemical phenomenon.

The phenomenon of smoldering combustion is usually the absence of visible light, smoke can be generated, slow combustion, temperature rise, etc., compared with flamed combustion, smoldering combustion is characterized by no obvious flame, compared with flameless combustion, smoldering can produce combustible gas through thermal decomposition. Smoldering can also be converted into flamed combustion under certain conditions and circumstances.

1. The flame retardant material is non-toxic and harmless, and there is no special smell of blindness.

2. Flame retardant materials are generally insoluble in water, non-flammable, and corrosion-resistant, and also have the function of anti-ultraviolet aging.

3. At present, the application of flame retardant materials has been very extensive, and there are many applications in the fields of construction, chemical industry, transportation, aerospace, shipbuilding, petroleum and metallurgy.