| Magnesium hydroxide is one of traditional important inorganic flame retardant materials, and magnesium sulfate whisker has the same character but also with the reinforcing function, both of them are high value-added products. Based on practical application, the preparation of magnesium hydroxide and type 153 basic magnesium sulfate whisker（MOS, MgSO4·5Mg（OH）2·3H2O） by the reaction of magnesium sulfate and ammonia were studied.Equilibrium data of quaternary system MgSO4-NH3·H2O-（NH4）2SO4-H2 O and related ternary system NH3·H2O-（NH4）2SO4-H2 O were determined by using isothermal method at25 ℃, and the composition of solid phase was analyzed. Based on the phase diagram, the optimum preparation conditions were determined by the analysis of the preparation temperature, reactive time, concentration of Mg2+ and the proportion of MgSO4·7H2O and NH3·H2O. Moreover, sodium stearate/EDTA composite modifier was used to improve the whisker length and to reduce the reunion. Activation index was worked as the modification measures and in situ test surface was used to modify the homemade MOS. The recycling program of mother liquor circulation was determined. On the basis of the static hydrothermal method, preparation of MOS whisker with dynamic hydrothermal was studied and the synthesis time is shorter, product appearance is more ideal. The kinetic equation MOS whisker was established according to the variation of concentration of Mg2+with the change of time, and the model parameter value and reaction order were calculated. |
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