改性氢氧化镁的制备及在HDPE中的应用

以低品位菱镁矿为原料,γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(KH570)为改性剂,通过蒸氨-沉镁改性-水热过程制备改性氢氧化镁KH570-Mg(OH)₂],改性剂在Mg(OH)₂生成体系中加入。采用吸油值、活化指数、红外光谱(FTIR)、X射线衍射(XRD)等手段对改性结果进行表征,在改性时间为60min,改性剂用量为2%,并进行水热处理工艺制备的Mg(OH)₂改性效果最好,改性后Mg(OH)₂活化指数达到了98.75%,吸油值为53.05 mL/100g,接触角为149°。整个工艺连续且可循环,为制备疏水性Mg(OH)₂工业生产提供实验基础。并将改性前后的Mg(OH)2应用于高密度聚乙烯(HDPE),测试其阻燃和力学性能,结果表明,KH570-Mg(OH)₂添加量为40%时,HDPE/KH570-Mg(OH)₂复合材料的氧指数为29.5%,达到阻燃级别,拉伸强度为18.40 MPa,断裂伸长率为217.11%,验证了改性后的Mg(OH)2与HDPE有较好的相容性。

Preparation of Modified Magnesium Hydroxide and Its Application in HDPE

Taking low-grade magnesite as raw material and silane coupling agent(KH-570)as modifier,modified magnesium hydroxide was prepared through the ammonia distillation-precipitation modification-hydrothermal process,and modifier was added during the Mg(OH)₂ generation process.The modification results were characterized by oil absorption value,activation index,Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD)and other methods.When modification time is 60 min and modifier dosage is 2%,the modification effect of Mg(OH)₂ prepared by the hydrothermal treatment process is the best.After modification,the activation index of Mg(OH)₂ could reach 98.75%,the oil absorption value is 53.05 mL/100g,and the contact angle is 149°.The whole process is continuous and recyclable,providing an experimental basis for industrial production.The Mg(OH)₂ before and after the modification were applied to high-density polyethylene(HDPE)to test its flame retardant and mechanical properties.The results show when the addition amount of Mg(OH)₂ is 40%,the oxygen indexof HDPE/KH570-Mg(OH)₂ composite material could reach 29.5%,which could achieve inflaming retarding level.The tensile strength is 18.40 MPa,and the elongation at break is 217.11%,which verifies that the modified Mg(OH)₂ has good compatibility with HDPE.