Enhanced crystallinity of micrometer-sized magnesium hydroxide by alkali metal hydroxide treatment
摘要
Mg(OH)2 with high chemical purity, enhanced crystallinity and anisotropic morphology is an important precursor in many application, especially in flame retardants. The platelet-shaped Mg(OH)2 with a (001) surface is important for fire resistance applications of Mg(OH)2-polymer composites. Mg(OH)2 was separated from sea bittern and micrometer-scale Mg(OH)2 polycrystals were successfully synthesized by a hydrothermal method at 180 °C. Surface treatment in aqueous solutions of alkali metal hydroxide before the hydrothermal step strongly influenced the crystal growth of Mg(OH)2. The synthesized Mg(OH)2 was characterized by X-ray diffraction, electron microscopy (SEM and TEM), particle size, and thermal analyses. The prepared Mg(OH)2 particles showed a mean diameter of 1000 nm and thickness of 80 nm. The growth conditions of the micrometer-sized Mg(OH)2 with high crystallinity were an alkali hydroxide solution of the concentration lower than 1.5 M for NaOH and lower than 0.5 M for LiOH, KOH and CsOH.