Research On The Preparation Of Superfine Magnesium Hydrate Which Have Special Microstructure By Brucite

As green additives to polymer material, Magnesium hydrate flame retardants are colorless, non-toxic, tasteless, non-corrosive nature. The morphology of magnesium hydrate affects the mechanical properties of polymer material. The magnesiuim hydrate which has a good morphology as orthohexagonal schistic or crystal whisker, will match well with raw materials and will not affect physical properties of raw materials, such as strength. And it will greatly improve the flexural strength and elongation of polymer materials. Therefore, a special morphology of magnesium hydrate flame retardants are superior in nature and more widely used.The brucite resources in Liaoning is rich. It accounts for about two-fifths of the total domestic reserves. The chemical composition of brucite is simple, and the decomposition temperature is low. So if use brucite to prepare magnesium hydrate, the raw materials is abundant, and the production process is green, it consumes less energy.The study namely applicated the methods of magnesium chloride and magnesium to prepare nano-magnesium hydrate which had special morphology under hydro-thermal condition, using brucite as raw materials sampling from Kuandian Brucite mine. It has a certain theoretical and practical significance. After XRD testing, it was proved that the purity and the degree of crystallization of the products were all high. After the analysis of SEM test, it was to see that the products were orthohexagonal schistic or crystal whisker, the crystal form was complete, and particle size were uniform. The outer radius of the orthohexagonal schistic was around 400 nm, the diameter of the crystal whisker was dozens of nanometers, the length was 2 to 5μm. The conclusions are as follow:1.the magnesium chloride method1) the preparation of the crystal precursor-Basic magnesium chloride is necessary. It affects the degree of crystallization, the dispersion of particles and the uniformity of size.2) influence factors:the temperature is on the impact of crystal growth rate significantly. Especially, when the temperature is 140℃, the degree of crystallinity and the uniformity of the particles size are perfect. Their radius are around 0.4μm;The primary role of stirring speed is to influence the growth direction of magnesium hydroxide crystals. When the speed of stirring is around 250 r/min, the products contain some magnesium hydroxide whisker with smooth, uniform nature; in addition, when the stirring speed is in 100～600 r/min, the magnesium hydroxide products are all orthohexagonal schistic;The degree of filling mainly affects the size of the crystal thickness. If the filling degree is bigger, the thickness of orthohexagonal schistic is smaller. Vice versa.The first reagent effectively control the the size of magnesium hydroxide crystal, while prevent the reunion of magnesium hydroxide particles; the second and third reagent's main role are similar to the first reagent, but the result is worse.2. the magnesia method1) influence factors:the first and third reagent effectively controlled the particle size and the integrity of crystal; the forth reagent encourage the magnesium hydrate to grow along single dimension to some degree.The solution concentration affected the growth direction of crystal. 2) the crystal degree of the products prepared by magnesium oxide or magnesium chloride are all in a high level. And the purity of the products prepared by magnesium chloride is higher.