The dddhhhGreen Guardiandddhhh of Plastics: Functions and Applications of Magnesium Hydroxide (Mg(OH)₂)
In today's plastics industry, with increasingly stringent safety and environmental regulations and heightened consumer safety awareness, flame retardants have become an indispensable component of many plastic products. Among numerous flame retardants, magnesium hydroxide (Mg(OH)₂), with its unique environmental advantages and highly efficient flame-retardant properties, is hailed as a dddhhhgreen flame retardantdddhhh and plays a crucial role in the field of polymer materials.
I. Core Function: Highly Efficient Flame Retardant
The most important and core function of magnesium hydroxide in plastics is as a flame retardant and smoke suppressant.
Its flame-retardant principle is not achieved by interrupting the combustion chain through a chemical reaction, but rather through physical pathways and multiple effects, mainly including the following three aspects:
1. Endothermic Decomposition (Cooling Effect)
Magnesium hydroxide has a very high decomposition temperature, approximately 340℃. When plastic burns, the ambient temperature rises, and magnesium hydroxide undergoes the following decomposition reaction:
Mg(OH)₂ → MgO + H₂O
This reaction is a strong endothermic reaction, absorbing a large amount of heat from the combustion zone, effectively lowering the surface temperature of the plastic material, making it difficult to maintain the thermal decomposition temperature, and delaying or even stopping the combustion process.
2. Oxygen Dilution (Covering Effect): The water vapor (H₂O) produced by decomposition rapidly dilutes the oxygen concentration in the air above the plastic surface. Combustion requires fuel, oxygen, and heat; the decrease in oxygen concentration directly inhibits combustion.
3. Formation of a Protective Layer (Barrier Effect): The magnesium oxide (MgO) produced after decomposition is a high-temperature resistant solid residue. It can form a dense protective layer covering the material surface together with the carbonized plastic matrix. This protective layer can isolate oxygen and heat, prevent internal combustibles from continuing to participate in combustion, and inhibit the escape of toxic fumes and combustible gases.
II. Unique Advantages: Why Choose Magnesium Hydroxide? Compared to aluminum hydroxide (Al(OH)₃), another commonly used inorganic flame retardant, magnesium hydroxide has the following significant advantages:
Higher thermal stability: Its decomposition temperature (340℃) is much higher than that of aluminum hydroxide (approximately 200℃), allowing it to be used in engineering plastics with higher processing temperatures, such as nylon (PA), polypropylene (PP), and polyethylene (PE), without premature decomposition during plastic processing.
Excellent smoke suppression performance: Magnesium hydroxide is particularly effective in suppressing smoke produced during plastic combustion, significantly reducing the emission of toxic and corrosive fumes and buying valuable time for evacuation in a fire.
Environmentally friendly and non-toxic: Magnesium hydroxide itself is non-toxic and non-corrosive, environmentally friendly during production, processing, and use, producing no harmful substances and complying with RoHS, REACH, and other environmental directives.
Neutralization of acidic gases: During combustion, it can neutralize acidic gases (such as HCl and SO₂) produced by plastics, further reducing secondary hazards.
