六亚甲基四胺对硅气凝胶的扩孔研究

以正硅酸乙酯为硅源,用六亚甲基四胺为扩孔剂,采用溶胶-凝胶法,通过常压干燥制备二氧化硅气凝胶.着重考察了水解时间、焙烧温度等因素对二氧化硅气凝胶孔径的影响.采用FTIR、SEM、TG-DTA、N2吸附脱附等分析方法对二氧化硅气凝胶的骨架结构和表面基团、结构形貌和分散性、热稳定性和孔径等进行了表征.结果表明:用六亚甲基四胺扩孔后的样品保持了二氧化硅气凝胶的骨架结构以及良好的分散性、热稳定性、孔径较大;同时,二氧化硅气凝胶的孔径随着焙烧温度的增加而增大,水解时间为24h左右时二氧化硅气凝胶的孔径不再变大.

Study of Silica Aerogels' Enlarge Pore Hexamethylene Tetramine as Expenging Agents

Using tetraethoxysilane(TEOS) as the silica source,silica aerogels were prepared via sol-gel method and ambient drying process.Factors influencing the pore size of silica aerogels,such as hydrolysis time and the different roasting temperature were investigated.FTIR、SEM、TG and N2 adsorption/desorption were used to analyze and characterize the aerogels.Results show that the sample with hexamethylene tetramine keeps skeleton structure of silica,aerogels,good dispersivity,good thermal stability and larger pore size;then,the pore size of samples increased with the rise of roasting temperature,the pore size of silica aerogels no longer gets bigger at 24 h around when hydrolysis time increases from 12 h to 60 h.