With the continuous improvement of people's quality of life, there are also some dangers in life, the increase of electrical appliances, and many things that cannot be exposed to fire sources, which often make us hard to guard against. Therefore, in addition to being careful in life, We should also take the initiative to take some measures to prevent fires, so that we can feel more at ease in our lives. Flame retardants can effectively prevent the spread of fires. We can use them at home. Many friends who do not know flame retardants may think that it will be harmful to use them at home. In fact, the production and production of flame retardants are all It is protected and identified by national law, and you can use it with confidence. Let's take a detailed look at the role of flame retardants.
one. The endothermic effect of flame retardants:
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, radiating to the combustion surface and acting on the gas that has been vaporized. The heat required for the decomposition of combustible molecules into free radicals will be reduced, and the combustion reaction will be inhibited to a certain extent. Under high temperature conditions, the flame retardant undergoes a strong endothermic reaction, absorbs part of the heat released by combustion, reduces the temperature of the surface of the combustible material, effectively inhibits the generation of combustible gas, and prevents the spread of combustion. The flame retardant mechanism of Al(OH)3 flame retardant is to improve its flame retardant performance by increasing the heat capacity of the polymer, so that it absorbs more heat before reaching the thermal decomposition temperature. This kind of flame retardant fully exerts its characteristic of absorbing a lot of heat when combined with water vapor, and improves its own flame retardant ability.
two. Covering effect of flame retardant:
After adding the flame retardant to the combustible material, the flame retardant can form a glass-like or stable foam cover at high temperature, isolate oxygen, and have the functions of heat insulation, oxygen isolation, and preventing the escape of combustible gas, so as to achieve flame retardant Purpose. For example, when the organic phosphorus flame retardant is heated, it can produce a cross-linked solid substance or a carbonized layer with a more stable structure. On the one hand, the formation of the carbonized layer can prevent the polymer from further pyrolysis, and on the other hand, it can prevent the internal thermal decomposition products from entering the gas phase to participate in the combustion process.
three. Flame retardants inhibit chain reactions:
According to the chain reaction theory of combustion, it is free radicals that 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, 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 have the same or similar evaporation temperature as the polymer decomposition temperature. When the polymer is decomposed by heat, the flame retardant also volatilizes at the same time. At this time, the halogen-containing flame retardant and the thermal decomposition product are in the gas phase combustion zone at the same time, and the halogen can capture the free radicals in the combustion reaction and interfere with the chain reaction of the combustion.
Four. Non-combustible gas asphyxiating effect:
When the flame retardant is heated, it decomposes into a non-combustible gas, and the concentration of the combustible gas decomposed from the combustible material is diluted to 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 the combustion and achieving the effect of flame retardant.
With the expansion of the application of polymer composite materials and the increase in the amount of use, the application of flame retardant materials and flame retardant technology have also achieved certain development and progress. Flame retardants are widely used due to their wide variety and excellent flame retardant properties. In the future research on flame retardants, the development direction of flame retardants with high thermal stability and good compatibility should be more inclined.
The above is part of the knowledge about the safety of flame retardants, I hope to help you.
