- Influence of drying methods on fractal geometric characteristics of mesoporous silica aerogels
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- 论文类型： 期刊论文
- 发表时间： 2013-06-01
- 发表刊物： JOURNAL OF WUHAN UNIVERSITY OF TECHNOLOGY-MATERIALS SCIENCE EDITION
- 收录刊物： SCIE、EI、ISTIC
- 卷号： 28
- 期号： 3
- 页面范围： 476-482
- ISSN号： 1000-2413
- 关键字： silica aerogel; N-2 gas adsorption; surface fractal dimension; mesoporous structure
- 摘要： Chemical modification/ambient drying method and freeze drying method were introduced to research the synthesis of mesoporous silica aerogels. By analyzing N-2 gas adsorption/desorption isotherms, the fractal geometric characteristics of gels were focused. The overall surface fractal dimensions were determined by analyzing N-2 gas adsorption branch and a Frenkel-Halsey-Hill (FHH) equation was empolyed to determine surface fractal dimension D (f). It is found that, during ambient drying process, V (TMCS)/V (Wetgel) ratio plays a crucial role in the changes of geometric feature, the key point is 50%, when the ratio is lower, and surface roughness increases with the ratio, when it exceeds 50%, the surface is almost unaffected by the modification. While freeze drying always tends to get larger D (f), freeze drying process could cause a rough surface of the gels. Compared with traditional porosity and specific surface area analyses, fractal geometry may be expected to be favorable for mesoporous structural analyses of materials.
