SAXS法研究掺杂SiO_2干凝胶的孔结构特性

Porous structure characteristic of the additive silica xerogels by SAXS

利用溶胶-凝胶酸碱二步催化法和常压干燥法制备了掺有不同含量添加物的SiO2干凝胶。通过小角X射线散射实验,计算得到了各掺杂SiO2干凝胶的比表面积、胶体颗粒和孔隙的平均切割长度,并分析了添加物对SiO2干凝胶孔结构的影响。结果表明,加入TiO2粉末和短切纤维,能够获得高比表面积的SiO2干凝胶;而加入SiO2纳米颗粒及短切纤维降低SiO2干凝胶的比表面积,平均粒径变大;短纤维的加入可在一定程度上限制干凝胶的收缩。

Two-step acid-base catalyzed silica xerogels adding different amount of additives were prepared through sol-gel and ambient pressure drying.Specific surface area,colloid particles and the average chord length of these silica xerogels were calculated by SAXS measure.The changes of porous structure were compared between pure silica xerogels and the impure ones.The specific surface area was increased by adding TiO2 powder and short fibers.On the contrary,the specific surface area of modified silica xerogels was decreased and the average pore diameter was increaged by adding silica xerogels powder.The shrinkage was restrained in the course of drying by adding short fibers.