Overview of Magnesium hydroxide flame retardant materials


Magnesium hydroxide (MH),, Molecular formula is Mg (oH) 2, and the relative molecular weight is 58.33. White powder, crystallized in hexagonal or amorphous flakes. When heated, Magnesium hydroxide decomposes into magnesium oxide and water. The initial decomposition temperature is 340 ℃. When it reaches 430 ℃, the decomposition speed is accelerated. When it reaches 490 ℃, the decomposition is complete, and the decomposition heat absorption is 0. "kJ/g (44.8kJ/mol). The raw materials for producing Magnesium hydroxide flame retardant include natural mineral raw materials and liquid raw materials. The mineral raw materials are mainly magnesium containing non-metallic minerals, including Brucite, Magnesite, dolomite, etc; The liquid raw materials are mainly seawater, salt lake brine, and underground brine.

Magnesium hydroxide, as a flame retardant filler of polymer matrix composites, has been used in plastics, rubber, cable and other materials. The flame retardant mechanism of Magnesium hydroxide is considered as follows:

1) It has a much larger heat capacity than polymers, so it can absorb a large amount of heat before thermal decomposition.

2) The large amount of water released by thermal decomposition (with a dehydration amount of 30.9%) absorbs a large amount of heat (about 1370J/g), thereby reducing the actual temperature of the surface flame of polymer materials, slowing down their degradation rate, and reducing the production of combustible gases.

3) The large amount of water vapor released during the decomposition process can cover the flame, reduce the oxygen concentration in the combustion surface air, and dilute combustible gases.

4) The Mgo produced after decomposition is a good refractory material that covers the surface of the polymer to block heat conduction and radiation, thereby improving the polymer's ability to resist flames, isolating air, and preventing combustion; The highly active MgO layer can also adsorb many substances (including free radicals and carbon) and promote the carbonization of polymer materials, promoting the rapid formation of a carbonized layer during combustion.

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