常压干燥制备疏水性SiO_2-玻璃纤维复合气凝胶及表征

以正硅酸乙酯(TEOS)和甲基三乙氧基硅烷(MTES)为复合硅源,玻璃纤维为增强体,采用溶胶-凝胶和常压干燥工艺制备出疏水性SiO2-玻璃纤维复合气凝胶。利用N2吸附脱附、扫描电镜、高分辨透射电镜、红外光谱、接触角、热重-差热分析及力学测试等手段表征复合气凝胶,并分析预处理玻璃纤维时的盐酸浓度及浸泡时间对复合气凝胶密度的影响。结果表明:当玻璃纤维的预处理条件为2.5mol/L盐酸浸泡0.5h时,制备得到的SiO2-玻璃纤维复合气凝胶表观密度最低,为0.12g/cm3,孔径主要分布在2~50nm,疏水角为142°,热稳定性温度高达500℃,抗压强度为0.05MPa,弹性模量为0.5MPa。

Preparation and Characterization of Hydrophobic SiO2-glass Fibers Aerogels v ia Ambient Pressure Drying

Hydrophobic SiO2‐glass fibers aerogels were prepared by sol‐gel process with tetraethoxysil‐iane (TEOS) and methyltriethoxysilane (MTES) as the silica source ,glass fibers as reinforcement , followed by ambient pressure drying .The physical properties and microstructure of silica aerogels were characterized by nitrogen adsorption/desorption tests ,Fourier transform infrared spectroscopy , thermogravimetric and differential thermal analysis , scanning electron microscopy , high resolution transmission electron microscopy ,contact angle measurement and mechanical testing .The influences of acid concentration and soaking time during pretreatment of glass fibers on the densities of SiO2‐glass fibers aerogels were investigated .The results show that when the pretreatment condition of glass fibers is soaking 0 .5h at 2 .5mol/L hydrochloric acid ,the obtained monolithic SiO2‐glass fibers aerogels exhibit the lowest density of 0 .12g · cm -3 and pore size is in the range of 2‐50nm ,the water contact angle is 142° ,the thermal stability temperature reaches 500℃ , the compressive strength is 0.05M Pa ,and the elastic modulus is 0 .5M Pa .