Effect of sulfate ion on synthesis of 5 Mg(OH)(2)center dot MgSO4 center dot 3H(2)O whiskers using non-hydrothermal method with acid catalyst

Abstract

Magnesium hydroxide sulfate hydrate (5 Mg(OH)(2)center dot MgSO4 center dot 3H(2)O, abbreviated 513 MHSH) whiskers are widely used in fillers and reinforcements of polymers and plastics. In general, the 513 MHSH whiskers can be prepared using several precursors, typically MgSO4 and base catalyst, via hydrothermal method at high temperature (140-200 degrees C). In this work, high-purity 513 MHSH whiskers were synthesized by non-hydrothermal method using MgO and H2SO4 as reactants, adjusting the amount of sulfuric acid and reaction time. In this process, sulfate ions, controlled by sulfuric acid, affect the formation and one-dimensional growth of 513 MHSH whiskers. In particular, the products produced were different, such as Mg(OH)(2), 513 MHSH and MgSO4, according to SO42- ion concentration. And high-purity 513 MHSH was obtained when the ratio of SO42-/Mg2+ was maintained in the range of 0.5-0.7. The morphologies and phase of the 513 MHSH were characterized by X-ray diffraction and scanning electron microscopy.