The Study Of Surface Modification And Applications Of Magnesium Hydroxide

This paper is aimed at solving the problem that caused by the high loading of magnesium hydroxide in the polymer matrix, which leads to the declined mechanical performance of composite materials, detailed program as follows:Project A:Firstly, the magnesium hydroxide modified by the silane A-172, then grafting vinyl acetate polymer to the vinylated magnesium hydroxide, this method was proposed forthe first time. Project B:The silane-vinyl acetate copolymer was prepared, which was used to modified the magnesium hydroxide.While the modification process conditions were determined preliminarily by direct and indirect test, meanwhile we discussed the possible modification mechanism. The experimental results are as follows:(1) The appropriate process conditions were determined by grafting vinyl acetate polymer to the vinylated magnesium hydroxide:The dosage of silane coupling agent A-172is3wt%; the modification temperature is80℃; the modification time is60min; The molar ratio of silane and vinyl acetate is3:1; grafting modification temperature is65℃; and the grafting modification time is5h. Under the modified conditions, the tensile strength and elongation of MH/EVA composites reached7.28MPa and199%respectively.(2) The suitable modification process conditions of magnesium hydroxide which modified by the prepared silane-vinyl acetate copolymer:(a), the wet modification of magnesium hydroxide by the copolymer:the molar ratio of silane and vinyl acetate is3:1; the dosage of copolymer is3wt%; the modification temperature is65℃; and the modification time is60minutes,(b). the dry modification of magnesium hydroxide by the copolymer(number average molecular weight is1361):the molar ratio of silane and vinyl acetate is3:1; the dosage of copolymer is3wt%; and the modification time is6minutes. Under the wet modified conditions, the tensile strength and elongation of MH/EVA composites reached7.84MPa and249%respectively.the tensile strength and elongation of dry modified MH/EVA composites reached8.0MPa and274%respectively. Compared with the Martin company’s MAGNIFIN H5product which filled in the same conditions, both of them have the equal value of tensile strength, while the former’s elongation6.2%higher than the latter. The modified MH/EVA composites’flame retardant grade reached the level of V-0, through the vertical burning test, and it achieved the requirements of industrial application.