Study Of Magnesium Hydroxide Surface Modification And Its Performance In EVA Composite

In this thesis, magnesium hydroxide(MH) powder was modified by a silane coupling agent VP10 through wet and dry modification process.According to testing the activation index and oil absorption rate, the optimum technological conditions of the wet and dry modified methods were determined as follows :(1) for a wet modified method, a stirring rate was40 rpm, VP10 prehydrolysis time 60 min, MH slurry concentration 20wt%, modified temperature 50?, modified time 30 min, a VP10 dosage of 3.5wt%;(2) for a dry modified method, a stirring rate was 1000 rpm, a VP10 dosage of 1wt%, modified time 10 min,modified temperature 100 ?.Magnesium hydroxide was synthesized using magnesium sulfate and ammonia as the raw materials through the hydrothermal method.The results showed that the diameter of MH product were increased, and the morphology of MH was more nearly to hexagonal plate with the increasing hydrothermal reaction temperature. Aitemag MH,Albemarle MH,self-synthesis MH were modified by VP10 through wet and dry modification processes. The modified result and VP10 modification mechanism of the above three MH were researched by settling curve, SEM, XRD, thermal gravimetric analysis and FT-IR.The results showed that the stability and dispersion of modified MH in a non-polar solution were improved. And the thermal stability was increased, so it was more conducive to the property of flame retardancy. According to FT-IR, the process of MH modified by VP10 was not a simple physical coating, but VP10 hydrolyzed to silanol condensation with hydroxyl groups of MH surface, and VP10 self-polymerized to siloxane grafted onto the surface of MH.In addition, three different MH and modified MH powder were added to EVA, the rheological and mechanical properties of MH / EVA composites were studied in the same MH amount. The results suggested as follows that :(1) for the rheological properties,self-synthesis MH best, followed by Albemarle MH, Aitemag MH worst;(2) for the elongation the at break : self-synthesis MH best, followed by Albemarle MH, Aitemag MH worst;(3) for Tensile strength: Aitemag MH best, followed by self-synthesis MH,Albemarle MH worst. The three modified MH by VP10, the rheological and mechanical properties of the composite system were improved. For the three MH, there are pros and cons to both the dry and wet modified processes, they can be selected according to the desired specific performance requirements of the material in industry.