Abstract:Preparation of superfine magnesium hydroxide with the bittern and ammonia was studied. The properties of the products were analyzed by laser granularity, X-ray diffraction, scanning electron microscope, the limiting oxygen index and the wetting angle measurements. The results show that the mean particle size of the magnesium hydroxide is about 230 nm with a platelet shape and the specific surface area is about 48 m2/g when the temperature is 55 ℃, and the ammonia and bittern are instilled simultaneously during the reaction process. After the modification, the limiting oxygen index and physical chemistry performance of the magnesium hydroxide were examined. The results show that the contact angle of magnesium hydroxide is 132.5˚ and the limiting oxygen index is 31.5 %, indicating that the modified magnesium hydroxide is an effective flame retardant and can be applied as flame retardant additives of the macromolecule compounds such as plastic, synthetic rubber and synthetic fibre.

Key words: bittern; ammonia; magnesium hydroxide; Mg(OH)2; flame retardants; limiting oxygen index