Why can aluminum hydroxide play a flame retardant effect?
Aluminum hydroxide is a kind of inorganic flame retardant additive with large dosage and wide application. It can not only achieve the flame retardant effect in use, but also prevent smoke and no dripping. So why can it be used as a flame retardant, what is the principle?
aluminum hydroxideIt is an inorganic flame retardant additive with large dosage and wide application. It can not only achieve the flame retardant effect in use, but also prevent smoke and no dripping. So why can it be used as a flame retardant, what is the principle?
Aluminum hydroxide is used as a flame retardant because it can decompose chemically bound water (about 34.6%) at high temperatures. This decomposition reaction is an endothermic reaction, thus delaying the thermal degradation rate of polymers, slowing down the combustion of polymers, the temperature rise of polymers, and promoting carbonization and smoke suppression. In addition, the released large amount of water vapor can dilute the concentration of combustibles and reduce the contribution of combustible gas to combustion, resulting in a decrease in the amount of heat release and smoke production of the system, which also helps to interrupt combustion.
When aluminum hydroxide is decomposed by heat, it releases water and absorbs a large amount of latent heat at the same time, which reduces the actual flame temperature on the surface of the material and slows down the degradation rate of polymer into low molecules, thus reducing the occurrence of combustibles. The uniformly released water vapor dilutes the concentration of oxygen on the surface and makes the surface combustion impossible. The decomposition temperature of aluminum hydroxide is about 205°C, and the dehydration reaction has been basically completed at 320°C, releasing crystal water, absorb latent heat and reduce the temperature (that is, the "cooling technology" in flame retardant technology, the large amount of water vapor generated can dilute the combustible gas.
In short, under the action of the flame, the aluminum hydroxide filled into the polymer decomposes and absorbs part of the heat released during the combustion process, which is equivalent to taking away heat from the polymer, thereby reducing the temperature of the polymer and slowing down the degradation rate. The chemical cooling effect of this dispersion heat absorption is the main reason why it can be flame retardant. The water vapor released by the decomposition of aluminum hydroxide can dilute the concentration of the gaseous reactants in the flame region and have a certain cooling effect. Filled into the polymer, it helps to form a carbonized layer during combustion, which can block heat and oxygen from entering, and can block the escape of small flammable gases. Of course, the latter two flame retardant effect is much smaller than the previous one. It can also effectively slow down the burning speed of the polymer, reduce the amount of smoke generated by combustion, and can also capture harmful gases. From the use of the situation, aluminum hydroxide and some organic additive flame retardants are different, will not produce corrosive combustion products, will not evaporate from the polymer and exudation.
Aluminum hydroxide is used as a flame retardant and is widely used, and the amount used is increasing.
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Everyone knows that there are two common flame retardants. Today we are going to talk about only one of them. Aluminum hydroxide flame retardant is an environmentally friendly halogen-free flame retardant, which can be widely used in fabrics, wood, plastics, and rubber., Polyurethane and other industries have ideal flame retardant effect. In the process of industrial application, it is found that flame retardant failure occurs when aluminum hydroxide flame retardant is added. The following are the reasons for the failure of aluminum hydroxide flame retardant, how to prevent it, how to deal with the operation, and restore the original function.
As a flame retardant, magnesium hydroxide also need to improve what aspects?
When it comes to flame retardants, everyone is familiar with them. Although we usually have less contact with them, we can know what they are used for from the name. Have to talk about magnesium hydroxide, we all know that its main presentation state is a granular, at present, the market sales of magnesium hydroxide particle size is larger, part of the commodity particle size up to tens of microns, immediately used as a flame retardant, poor dispersion, the physical properties of raw materials greater harm. In industrial production, physical grinding methods are generally used to reduce the particle size to 1 micron. The surface of magnesium hydroxide has high polarity and is easy to agglomerate. As the compatibility of refractory materials and polymer substrates, it not only reduces its flame retardant grade, but also causes more serious harm to the physical properties of raw materials.
Hefei Zhongke Flame Retardant New Material Co., Ltd
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