Magnesium hydroxide is converted between 340℃ and 490℃, and its heat absorption energy is 187cal/g.

　　The average initial conversion temperature of magnesium hydroxide is much higher than that of alumina hydrate. It has good heat stability, excellent flame retardant grade and smoke removal effect. It is very suitable for the production and processing of polyolefin plastic products with higher average temperature.

　　When Mg(OH)2 is applied to PP (the addition amount is more than 50%), it has an excellent flame retardant level effect. When Mg(OH)2 is applied to PE, its flame retardant level effect is stronger than AI(OH)3.

　　This is due to magnesium hydroxide in the ignition not only achieve dehydration chemical reaction, but also on the polymer has the corresponding carbonization effect to produce a layer of protective layer, with a flame-retardant efficiency.

　　Under the same amount of addition, different proportions of aluminum hydroxide and magnesium hydroxide have no significant difference in the efficacy of flame retardancy grade, but the efficacy of the two combined applications is better than that of the direct application. Although both of them require dehydration chemical reactions, there are differences in the average conversion temperature and endothermic energy.

　　Magnesium hydroxide requires a higher average temperature to dehydrate and is carbonized at the same time.

　　The heat absorption of magnesium hydroxide is relatively small, because the effect of controlling the average temperature rise of the material is not as good as that of aluminum hydroxide, the two applications can be combined to fill each other, its flame retardant grade is better than the direct application effect.

　　Magnesium hydroxide has a good smoke suppression effect. The smoking duration of PP specimens containing Mg(OH)2 was significantly delayed at the beginning, and the maximum smoking volume and the smoking volume after 4min were much lower than those of PP specimens containing halide /Sb2O3.

　　For this reason,Mg(OH)2 is an efficient smoke-removing filler for PP under the standard of moderate dosage.

　　Poor acid resistance of Mg(OH)2, it will dissolve rapidly in the acid, and it is also easy to be interfered by lactic acid and leave fingerprints on the surface of the product.

　　In order to get rid of the defects of dispersivity and mismiscibility of Mg(OH)2, it is necessary to develop and design good varieties with miscibility.

　　The way to improve the grain size distribution and agglutination reaction characteristics of crystals can be selected, and the way to implement surface treatment of unsaturated high fatty acids, saturated fats and multi-component with excellent thermal conductivity can also be chosen.

　　The principle of the flame-retardant grade of magnesium hydroxide is given: when magnesium hydroxide encounters heat (340-490 degrees), it generates the surface heat energy of the adsorbent and has the flame-retardant grade effect.

　　At the same time, a lot of water vapor is released to dilute the oxygen on the surface of the fuel, and the active magnesium oxide formed by the transformation sticks to the surface of the combustible material, which further blocks the realization of ignition.