Synthesis Of Magnesium Hydroxides By Vapor Hydration And Their Application On Flame Retardation

Recent years,magnesium hydroxide flame retardant,because of its environmentallyfriendly has drawn widespread attention.Magnesium hydroxide as flame retardant was mainly made from natural brucite,however,the amount of the brucite is finite（about 15 million tons）,recent years,along with the increasing of exploiting lead to the available high-grade brucite become depleted gradually.The researchers expected to utilized magnesite（3 billion tons reserves）and brucite（about 3.5 billion tons reserves）which have abundant reserves to synthesis magnesium hydroxide.Abundant researches shows that magnesium hydroxide were synthesis by direct hydration process use magnesite light baking powder（Light burned magnesia）as material was the most direct,effective and low cost.On the other side,due to the polarity of the surface of magnesium hydroxide is very strong,hydrophilic and hydrophobic oil,so when fills magnesium hydroxide into polymer will cause mechanics performance of the material deteriorated sharply.In earlier studies,the research group that the author belongs to established a new way to synthesis magnesium hydroxide by vapor hydration.Based on these,fatty acids were introduced into during the gas phase hydration process in this thesis so that realize the goal that required modified magnesium hydroxide from light burned magnesia only by one step,The main research contents are as follows:（1）Study on the synthesis and modification of magnesium hydroxide by vapor hydration entraining modifier method.In the presence of magnesium oxide as raw material,the effect of caprylic acid,decanoic acid,lauric acid as modifier on hydration and modification were investigated study first.After analyzing the oil absorption value and contact angle,we found that the most ideal modifier is lauric acid,so in the presence of lauric acid as modifier,the effect of reaction conditions on modification of magnesium oxide was mainly investigated and the optimal conditions of surface modification were found to be as follows: 5.0wt.% lauric acid used as modification agent,180℃（modification temperature）and 28h（modification time）,4mm（the height of powders）;the unmodified Mg（OH）₂ and modified Mg（OH）₂ were characterized by FI-IR and XRD,the result showed that lauric acid was dispersed on the surface of magnesium hydroxide powder.（2）Study on the synthesis and modification of magnesium hydroxide by vapor hydration under the condition of the modifier and magnesium oxide were mixed.In the presence of magnesium oxide as raw material,the effect oftridecylic acid,myristic acidstearic acid and oleic acid as modifier on hydration and modification were investigated study first.After analyzing the oil absorption value and contact angle,we found that the most ideal modifier is myristic acid and stearic acid,so in the presence of myristic acid and stearic acid as modifier,the effect of reaction conditions on oil absorption value and contact angle was mainly investigated and the optimal conditions of surface modification were found to be as follows: 4.5wt.% myristic acid used as modification agent,180℃（modification temperature）and 4 hours（modification time）,10 millimeters（the height of powders）;35wt.% stearic acid used as modification agent,180℃（modification temperature）and 6 hours（modification time）,8 millimeters（the height of powders）;the unmodified Mg（OH）₂ and modified Mg（OH）₂ were characterized by FI-IR and XRD,the result showed that myristic acid and stearic acid was dispersed on the surface of magnesium hydroxide powder.（3）Study of modified mechanical properties and flame retardance flame retardant properties.The Mg（OH）₂/EVA plastic composites were were prepared by magnesium hydroxides was filled into the EVA,and the mechanical properties and flame retardance flame retardant properties of the composites was investigated.The results showed that modified magnesium hydroxide could improve the mechanical properties of materials while improving the flame retardant properties of the materials obviously compare with the unmodified magnesium hydroxide,and they could meet the standard of UL-94 V-1 level.