摘要
采用溶胶-凝胶法结合超临界流体干燥技术制备了SiO2气凝胶,系统地考察了醇硅比、水硅比、体系pH值等制备条件对SiO2气凝胶胶凝时间、孔径分布及孔型结构的影响。结果表明,水硅比对气凝胶的孔径分布和孔型具有较大的影响;水用量增加,胶凝时间延长,气凝胶的孔径分布逐渐变窄,孔型趋于一致。乙醇不参与溶胶-凝胶反应,只对TEOS有助溶和稀释的作用,因此乙醇用量增加,溶胶的胶凝时间延长,但对体系反应的影响相对较小,不会引起气凝胶孔结构的剧烈改变。在较小pH值或弱碱性范围内,pH值对孔形结构的影响也比较小,体系pH值增大,胶凝时间缩短,制得的气凝胶孔径分布较窄,孔型均一。当pH值大于8.5后,不利于气凝胶网络结构的形成和均匀分布,胶凝时间随pH值的增大而延长,制备的气凝胶孔径和孔型分布都比较大。
SiO2-aerogel nanoporous super thermal insulation material is prepared via sol-gel method and ethanol supercritical drying. The influence of the pH value of the original hydrogel, the ratio of EtOH/TEOS and H2O/TEOS on the gelling time, pore distribution and porous structure of aerogel are investigated. The results show that the ratio of EtOH/TEOS has distinct effect on the SiOz-aerogel. The gelling time is prolonged with the increase of the water, and the pore distribution and porous structure of aerogel are tending to become homogeneous. For the diluted function of the ethanol, the gelling time is increased with the increase of the ethanol, and the effect on the pore distribution and porous structure is moderate. When the pH value is less than 8. 5, the gelling time is shortened with the increase of the pH, and the pH value has a mild influence on the pore of aerogel. But when the pH value is more than 8. 5, the effect becomes intense, the gelling time is increased with the increase of the pH sharply, and the pore distribution broadens out rapidly at this point.
出处
《材料导报》
EI
CAS
CSCD
北大核心
2009年第12期102-105,共4页
Materials Reports
基金
贵州省优秀教育科技人才省长基金项目(2005-111)
贵州省工业攻关项目(20063030)
