热处理温度对气相法二氧化硅性能的影响

Influences of Heat Treatment Temperatures on the Properties of Fumed Silica

研究了热处理温度对气相法二氧化硅(HL-200和HL-380)硅羟基质量分数、热失重、比表面积、p H值及HL-200在热硫化硅橡胶中应用性能的影响。结果表明,随着热处理温度的提高,气相法二氧化硅中硅羟基的质量分数先保持稳定后下降,并最终再次趋于稳定;HL-200的质量损失率从0.45%缓慢波动升至1.15%;HL-380的质量损失率从500℃开始较快升高,由2.5%升至4.46%;气相法二氧化硅的比表面积总体逐渐减小;HL-200的p H值在150~900℃先升后降,超过900℃后趋于稳定;HL-380的p H值在500~1100℃先升后降,超过1100℃后再次升高;当采用HL-200作热硫化硅橡胶的补强填料时,较佳的热处理温度为600℃。

The effect of heat treatment temperatures on the mass fraction of hydroxyl group,thermal weight loss,specific surface area,p H value for fumed silica(HL-200 and HL-380)and the application performance of HL-200 in HTV silicone rubber were investigated.Results show that as heat treatment temperature increases,the mass fraction of silanol in fumed silica first stabilizes,then decreases,and finally tends to be stable again;the mass loss rate of HL-200 slowly fluctuates from 0.45%to 1.15%.The mass loss rate of HL-380 increases rapidly from 500℃,from 2.5%to 4.46%.The specific surface area of fumed silica gradually decreases.The pH value of HL-200 rises and then decreases from 150 to 900℃,and stabilizes after exceeding 900℃;the pH value of HL-380 rises firstly and then falls during 500~1100℃,and then rises again after exceeding 1100℃.In addition,when HL-200 is used as a reinforcing filler in HTV silicone rubber,the preferred heat treatment temperature is 600℃.