Magnesium carbonate whiskers are an inorganic material with excellent flame retardant properties. Its flame retardant performance mainly comes from the following two aspects:
Magnesium carbonate whiskers have high thermal stability and decompose at high temperatures to release carbon dioxide and water vapor, forming a heat insulation layer to prevent heat transfer and inhibit the spread of fire.
Magnesium carbonate whiskers have a large specific surface area, which can absorb a large amount of heat and smoke, reducing combustion temperature and smoke concentration.
The preparation of magnesium carbonate whiskers by reverse precipitation is currently the most commonly used preparation method. The principle of this method is to add carbonate to an alkaline solution to decompose the carbonate to generate carbonate ions, and then add Mg2+ ions to react with the carbonate ions and Mg2+ ions to generate magnesium carbonate whiskers.
The preparation process of magnesium carbonate whiskers by reverse precipitation method mainly includes the following steps:
① Prepare an alkaline solution. Generally, sodium hydroxide or sodium carbonate solution is used as the alkaline solution.
② Add carbonate. Carbonate can be sodium carbonate, sodium bicarbonate, ammonium bicarbonate, etc.
③ Add Mg2+ ions. Mg2+ ions can be magnesium sulfate, magnesium chloride, etc.
④ Adjust pH. Adjustment of pH value can affect the morphology and particle size of magnesium carbonate whiskers.
⑤ Separate and dry. Separation and drying can obtain pure magnesium carbonate whiskers.
The preparation of magnesium carbonate whiskers by the reverse precipitation method has the following advantages:
① The process is simple and the equipment is easy to operate.
② The cost is low and the raw materials are easy to obtain.
③ Magnesium carbonate whiskers with different morphologies and particle sizes can be prepared.
The flame retardant performance of magnesium carbonate whiskers mainly depends on its morphology, particle size and dispersion. Generally speaking, magnesium carbonate whiskers with larger aspect ratio have better flame retardant properties. In addition, the dispersion of magnesium carbonate whiskers also affects its flame retardant properties. Magnesium carbonate whiskers with better dispersion can be more evenly distributed in the matrix material, thereby exerting a better flame retardant effect.
Magnesium carbonate whiskers can be used in various flame retardant materials, such as plastics, rubber, fibers, coatings, etc. Among these materials, magnesium carbonate whiskers can play the following roles:
Improve the flame retardancy of materials.
Improve the material’s heat and weather resistance.
Reduces combustion smoke and toxic gas emissions from materials.
Magnesium carbonate whiskers are flame retardant materials with broad application prospects. With the continuous deepening of research, the flame retardant properties of magnesium carbonate whiskers will be further improved, and their application scope will be wider.
The following is the research progress on the preparation of magnesium carbonate whiskers by reverse precipitation method and its flame retardant properties:
The researchers used sodium dodecyl sulfate (SDS) as an additive to prepare magnesium carbonate trihydrate whiskers with a large aspect ratio. Studies have shown that SDS can inhibit the agglomeration of magnesium carbonate whiskers, thereby increasing the aspect ratio of the whiskers.
Researchers used ultrasound-assisted technology to prepare high-purity magnesium carbonate whiskers. Research shows that ultrasonic waves can destroy the adsorption layer on the surface of whiskers, thereby improving the purity of whiskers.
Researchers used solvent-assisted technology to prepare magnesium carbonate whiskers with composite functions. Research shows that composite functional magnesium carbonate whiskers have better flame retardant properties.
In the future, the preparation process of magnesium carbonate whiskers will become more mature, its flame retardant properties will be further improved, and its application scope will be broader.