| The optics, electric, thermodynamics and magnetism properties of magnesium hydroxide nanorods are very different from the common magnesium hydroxide. The magnesium hydroxide nanorods is widely used in flame-retardant area, nano-magnesium oxide ceramic, neutralizer in environment protecting field, desulfurizer in flue gas and so on. Common magnesium hydroxide as flame-retardant will be effective when the loading is as high as 40 percent., which will largely decrease the mechanical property. The product of magnesium hydroxide nanorods will help to solve the problems. The liquid method concerning the preparation method of magnesium hydroxide nanorods is the most common method and there are some other methods such as liquid-solid arc discharge technique and Pulsed-laser ablation of Mg in liquids.The magnesium hydroxide nanorods were prepared by precipitation conversion method, using basic magnesium chloride as precursor and sodium hydroxide as precipitation conversion agent. The effects of these reaction factors, such as the solvent, mol ratio of reactants and concentration of sodium hydroxide etc, to the morphology of magnesium hydroxide nanorods, were studied. The products are characterized and detected by the following means, such as the X-ray diffraction, Scanning Electron Microscopy (SEM) and so on. The results indicate that the solvent and the morphology of basic magnesium chloride are the main effecting factors. The best condition of the preparation of reactants is as followed: the solvent is ethanol; the mol ratio of sodium hydroxide to basic magnesium chloride rods is 2:1; the concentration of sodium hydroxide is 2mol/L; reaction temperature is 60℃; reaction time is 1 hour. Well-crystallized single-crystal magnesium hydroxide nanorods with diameter of 100-200nm and length of 6μm were obtained.Magnesium chloride hexahydrate (MgCl2·6H2O) , urea(H2NCONH2) , magnesium oxide(Light) and ammonia were the reactants, and different morphological magnesium hydroxide materials were prepared by liquid phase method. The drying curves and drying rate curves were obtained by drying kinetics experiments. The equilibrium moisture adsorption isotherms of magnesium hydroxide of three morphological micro-nanostructures at room temperature were gained. The results indicate that drying rate curves of magnesium hydroxide microparticles exhibit three stages: a set-up period, a constant rate drying period and a falling rate drying period. And drying rate curves of magnesium hydroxide nanosheets( nanosheets1 and nanosheets2) show the similar three stages with a little descending trend in constant rate drying period. It is also found that the initial moisture contents, critical moisture contents and equilibrium moisture contents of Mg(OH)2 nanosheets are larger than those of Mg(OH)2 microparticles under the same drying conditions. The drying math models of nanosheets and microparticles are obtained. It is found that the results of simulation by drying math models are in good agreement with experimental data, and therefore drying math models found could adequately describe the drying behavior of the according micro-nano magnesium hydroxide products.The experiment of surface modification of magnesium hydroxide nanorods with stearic acide was processed. The modification effects of the dosage of stearic acide and modification time to magnesium hydroxide nanorods were investigated. The products were characterized and detected through the X-ray diffraction and IR analysis. It is shown that the dosage of stearic acide is 5% and the modified time is about 1 hour.
|
PDF Full Text Request