Research On The Preparation Of Magnesium Hydroxide Whisker By Direct Precipitation Method

China has rich minerals of magnesium, as well as the salt lake magnesium resources and seawater magnesium resources, the magnesium is full of variety and wide of distribution. We extract magnesium chloride from China’s affluet magnesium,and magnesium hydroxide whisker was prepared to add a precipitator and auxiliaries by direct precipitation method. Magnesium hydroxide whisker used as a flame retardant have characteristics of non-toxic smoke-free non-polluting.our country are long-term use of brominated flame retardants and other organic flame retardants, They has been limited due to amount of smoke and toxic to the environment by second pollution. Magnesium hydroxide whisker used as a material filler have better dispersity and compatibility to enhance stiffness and strength of composite material. It is great significance in magnesium resource utilization, environmental protection, as well as functional materials.Magnesium hydroxide whisker is prepared with magnesium chloride and alkali liquor as raw materials by direct precipitation method,.Its preparation process is mainly divided into four stages, namely precipitation reaction, crystallization reaction, washing process and drying process. We study the different processing conditions of magnesium hydroxide whisker in the preparation process, including the choice of precipitation agent, the choice of solvent, the choice of raw material ratio, the choice of detergent,the choice of drying temperature and drying time; choosing the additives of magnesium hydroxide whisker in its preparation process, including single additives, compounding additives and foreign ion additives. The results show that the magnesium hydroxide whisker can be prepared by direct precipitation method with NaOH as the precipitation agent, and ethanol/water (1:1) as solvent, MgCl2and NaOH reaction ratio is1:2, the zinc stearate or ferric chloride as additives, washing in G4sand core funnel with water+ethanol,,drying in vacuum drying oven with the vacuum degree of0.08Mpa and the drying temperature of100℃for the3h. The magnesium hydroxide whisker by prepared is uniformity particle size and integrity crystal.Magnesium hydroxide whisker is prepared to add zinc stearate or ferric chloride, the process conditions of its liquid reaction stage is optimized.The results are as follows:the process conditions for magnesium hydroxide whisker be prepared to add zinc stearate:the precipitation temperature is40℃, the crystallization temperature is90℃, the crystallization time is2h; the process conditions for magnesium hydroxide whisker be prepared to add ferric chloride:the precipitation time is40min, the precipitation temperature is50℃, the quanlity of foreign ion is0.4mol%. The SEM chart of is clear,no reunion phenomenon,and whisker aspect ratio is about10.7. In the XRD chart, the diffraction intensity of the (101) plane is increased.lt’s show that the growth of magnesium hydroxide whisker has preferred sexual orientation to add the additives.In the text,the growth of mechanism Magnesium hydroxide whisker are discussed. The growth kinetics of magnesium hydroxide whisker were analyzed from the point of crystal nucleation process and crystal growth rat, it’s proofed that whisker growth accord with the classical crystal growth theory. The foreign ions led to the preferential growth in the crystal growth process, it’s a guide crystal role in the form of magnesium hydroxide whisker; Mg (OH)6~4+anionic coordination octahedron is the growth units of magnesium hydroxide whisker. Anion coordination polyhedron growth units theory can reasonably explain growth and generation of magnesium hydroxide whisker.