Overview of the role and application of magnesium hydroxide

     Magnesium hydroxide is a new type of filling flame retardant that releases bound water during thermal decomposition, absorbs a large amount of latent heat, and reduces the surface temperature of the synthetic material it fills in flames. It has the function of inhibiting polymer decomposition and cooling the combustible gases produced.

Magnesium hydroxide is an inorganic flame retardant filler with promising application prospects in polymer based composite materials. Like aluminum hydroxide, magnesium hydroxide flame retardant relies on chemical decomposition to absorb heat and release water when heated, thus having the advantages of non toxicity, low smoke, stable chemical properties of magnesium oxide generated after decomposition, and no secondary pollution. However, compared with halogenated organic flame retardants, to achieve a comparable flame retardant effect, the filling amount generally needs to reach more than 50%. Due to the inorganic nature of magnesium hydroxide, its surface compatibility with polymer materials is poor. Such a high filling amount, if not surface modified, will result in a decrease in the mechanical properties of the composite material when filled into polymer materials. Therefore, surface modification treatment must be carried out to improve its compatibility with polymer based materials, so that the mechanical properties of the filling material do not decrease, and even some mechanical properties of the material can be improved.

    Experimental results have shown that unmodified magnesium hydroxide exists in the form of aggregates in PP. Although the powder itself is extremely fine, there are clear boundaries or even voids between the particle aggregates and the PP matrix due to the incompatibility between the particle surface and the PP matrix. The voids formed by the escape of magnesium hydroxide particles during brittle fracture indicate that unmodified magnesium hydroxide only serves as a filling and flame retardant in PP, and does not chemically bond with PP. The surface modified magnesium hydroxide is uniformly dispersed in the PP matrix, and the particles are mostly dispersed in the form of primary particles or small agglomerated particles in the material.

Magnesium hydroxide decomposes and releases water when heated, which can absorb a large amount of heat and lower the surface temperature of the material. Meanwhile, the released water vapor can dilute combustible gases and further suppress the spread of flames. In addition, magnesium oxide generated after the decomposition of magnesium hydroxide is a high-temperature resistant substance that can form a protective layer on the surface of the material, blocking the contact between oxygen and the material, thereby achieving flame retardant effect.

     Application fields of magnesium hydroxide

1. Plastic industry: Adding magnesium hydroxide to plastic products can significantly improve their flame retardant performance, making them less prone to combustion when exposed to a fire source, providing strong protection for people's lives and property safety.

2. Cable industry: As an important carrier of power transmission, the fire resistance of cables is crucial. The application of magnesium hydroxide in cable materials can effectively improve the fire resistance level of cables and reduce the occurrence of fire accidents.

3. Building materials: In the field of construction, magnesium hydroxide is widely used in the manufacturing of fireproof boards, fireproof coatings and other products, providing a solid barrier for the fire safety of buildings.