TEOS-28和TEOS-40及其配比对SiO_(2)气凝胶结构和性能的影响研究

Study on effect of TEOS-28,TEOS-40 and their proportions on structure and properties of silica aerogels

分别以TEOS-28和TEOS-40为硅源,通过酸碱两步法,经乙醇超临界干燥制备透明SiO_(2)气凝胶。对SiO_(2)气凝胶进行微观形貌、比表面积、导热系数、可见光透射率表征,探究TEOS-28和TEOS-40及其配比对SiO_(2)气凝胶结构及性能的影响。研究表明,相同配比条件TEOS-40作为硅源制备的SiO_(2)气凝胶性能更佳。TEOS-40为硅源的条件下,随着去离子水含量的增加,凝胶时间呈先降低后升高的趋势,可见光透射率呈逐渐降低趋势,导热系数呈先降低后升高的趋势。随着乙醇含量的增加,凝胶时间呈逐渐增加趋势,可见光透射率呈先增大后减小的趋势,导热系数则逐渐降低。

Using TEOS-28 and TEOS-40 as silicon sources,transparent silica aerogels are prepared by acid alkali two-step method and ethanol supercritical drying.The microstructure,specific surface area,thermal conductivity and visible light transmittance of silica aerogels are characterized to explore the influence of TEOS-28,TEOS-40 and their ratios on the structure and properties of silica aerogels.The results show that the performance of silica aerogels prepared with TEOS-40 as silicon source is better under the same ratio.When TEOS-40 is a silicon source,with the increase of deionized water content,the gel time decreases first and then increases,the visible light transmittance decreases gradually,and the thermal conductivity decreases first and then increases.And with the increase of ethanol content,the gel time gradually increases,the visible light transmittance first increases and then decreases,and the thermal conductivity gradually decreases.