硬脂酸改性氢氧化镁分散性能的研究

Research on Dispersing Performance of Magnesium Hydroxide Modified by Stearic Acid

采用硬脂酸在线修饰沉淀法制备的氢氧化镁颗粒,并重点考察了反应温度、加料方式和硬脂酸添加量对氢氧化镁颗粒分散效果的影响。通过粒度分析、红外、热重、扫描电镜以及活度分析等手段对硬脂酸改性氢氧化镁效果进行了详细的表征。结果表明:氢氧化钠加到氯化镁(正加方式)更有利于氢氧化镁晶体的生长,减少团聚;当反应温度为70℃时能有效促进硬脂酸的溶解,加强硬脂酸分子的扩散,改性效果明显优于常温;当硬脂酸的添加量为1%(相对于氢氧化镁)时改性效果最佳,颗粒平均尺寸减小至10μm。红外及热重分析结果表明硬脂酸通过化学键合吸附在颗粒表面;且扫描电镜和活度分析结果进一步证明通过硬脂酸改性后的氢氧化镁分散效果得到明显改善。

In this paper, magnesium hydroxide samples were prepared through precipitation with stearic acid as the additive. Special attention was given to reaction temperature, feed methods and additive amounts of stearic acid which influenced the dispersing effect of magnesium hydroxide particles. The surface modification results were evaluated by the means of Malvern laser particle size analyzer, FT - IR, TGA, SEM and active ratio analysis. The results indicated that the feed method of positive order promotes the growth of magnesium hydroxide particles and prevents the aggregation. With the addition of 1% stearic acid and the particle size of magnesium hydroxide decrease to 10 /xm at 70~C, it shows better modification effect than other investigated conditions. Thermal gravity analysis （TGA） and infrared analysis （IR） are used to prove that stearic acid is absorbed on the surface of magnesium hydroxide particles through chemical bond. Meanwhile, the results of scan- ning electron microscope （SEM） and active ratio analysis shows that the dispersing effect on magne- sium hydroxide particles improves obviously after the modification of stearic acid.