为了进一步改善气相白炭黑的分散性,利用中试流化床对其进行干法改性。选择高含碳量的聚二甲基硅氧烷(PDMS)为改性剂,考察了预活化、改性温度、时间、气速和改性剂质量分数对气相白炭黑疏水性能的影响。结果表明,最佳工艺条件为:预活化温度为200℃、预活化时间为30 min、用水质量分数为10%、氮气气速为4 Nm³/h、改性温度为300℃、改性剂PDMS质量分数为25%、反应时间为90 min。改性后气相白炭黑含碳量为4.89%,表面羟基量降为0.15个/nm²,可润湿率为0%,提高了气相白炭黑的疏水性。此外,探究了改性气相白炭黑对硅橡胶的补强性能,含碳量为2.5%的气相白炭黑补强时,断裂伸长率提高了24.8%,补强系数提高18.0%,拉伸强度提高8.0%,补强效果最佳,有效提升了硅橡胶的综合力学性能。

To further improve the dispersibility of fumed silica,a pilot-scale fluidized bed is utilized for its dry modification by using polydimethylsiloxane (PDMS) with a high carbon content as the modifying agent.The influences of pre-activation,modification temperature,time,gas velocity,and the mass fraction of the modifying agent on the hydrophobic properties of fumed silica are studied.Results indicate that the optimal process conditions are as follows:pre-activation temperature is at 200℃,pre-activation time is 30 min,water mass fraction is 10%,nitrogen gas velocity is 4 Nm³·h^-1,modification temperature is at 300℃,PDMS mass fraction is 25%,and reaction time is 90 min.After modification,carbon content of fumed silica is 4.89%,surface hydroxyl group content declines to 0.15 groups·nm^-2,and the wettable rate is 0%,which enhances the hydrophobicity of fumed silica.Furthermore,the reinforcing performance of the modified fumed silica on silicone rubber is explored.As fumed silica with a carbon content of 2.5% is used to reinforce,the tensile elongation at break of silicone rubber increases by 24.8%,the reinforcement coefficient increases by 18.0%,and the tensile strength up 8.0%,showing the best reinforcement effect and effectively improving the comprehensive mechanical properties of silicone rubber.

万小维(1999-),女,硕士生,研究方向为干法改性气相白炭黑及其应用,wwzjjkksl@163.com;胡彦杰(1979-),男,博士,教授,研究方向为燃烧合成功能纳米材料及其过程放大,通讯联系人,huyanjie@ecust.edu.cn。