| Magnesium hydroxide is mainly used as a fire retardant chemical of macromolecule material and its main merit is that it has a high decomposing point, when compared with other fire retardant chemicals.The use of magnesium hydroxide as an fire retardant chemical can avoid the qualitative change of plastic caused by the decomposing of fire retardant chemical when the thermoplastic material need a high temperature to be processed (200癈), and besides, nano magnesium hydroxide can be used as stuffing and intensifier in making rubber and plastic, as polymerization inhibitor in the field of medicine, as catalyzer in the field of chemical industry, as marerial of magnesian product, as asbestos fireproofing stuffing,as insulated or heat preservation material and so on. So the magnesium hydroxide has a good future. The study on magnesium hydroxide has much meaning.Nano magnesia is a new kind of high-function fine inorganic material which diameter is between 1 nanometer and 100 nanometers, There are differences in performance of optics, performance of calorifics, performance of mechanics, performance of chemistry between nano magnesia and ordinary magnesia. By using nano magnesia the sinter process can be carried out in a lower temperature without the use of agglomeration. The nano magnesia can also be used as agglomeration and stabilization in making zirconia , alumina, ferric oxide and other nano particles for high quality nano chinaware,The experiment show that the ethanol-water solvent of which the ratio is bewteen 1:1 and 1:2 is a ideal solvent for the preparation of nano magnesium hydroxide used as fire retardant chemical. Acerate or sheet magnesium hydroxide which diameter is between 50 nanometers and 100 nanometers can be prepared by using ethanol-water solvent. The best technical conditions for making nano magnesia are as follows: the reaction temperature for making magnesium hydroxide is between 25 C and 35 C; the reaction time is between 4 hour and 5hour, the ratio of MgCl2to NH3 H2O is 1:4.5; the concentration of MgCl2 is 0.40mol/L; the temperature for the preparation of magnesium hydroxide is 450C with time of three hour. The magnesia has uniform diameter which is about 28 nanometers.The nano magnesium hydroxide can affect the combustion inhibitor of PVC, when it is filled into the PVC as a fire retardant chemical. Burning velocity of PE/Mg(OH)2 drop markedly when the amount of filled Mg(OH)2 is rising. There are no marked difference in burning velocity between the pure PE with a velocity of 38mm/min and the PE filled with 1% ~ 3% Mg(OH)2 with a velocity of 37.5mm/min. But the burning velocity can be 8.15~0.34mm/min which can meet the requirements of GB2408-80/ II -8,when the amount of filled Mg(OH)2 is... |
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