Preparation of silica aerogels with improved mechanical properties and extremely low thermal conductivities through modified sol-gel process
Name
727067791-MIT.pdf
Description
Full printable version
Size
11.64 MB
Format
Adobe PDF
Checksum (MD5)
cf1d3942e3c864addfda3c545803e102
Author(s)
Zuo, Yanjia
Advisor(s)
Taofang Zeng and Gang Chen.
Date Issued
2010
Publisher
Massachusetts Institute of Technology
Abstract
Reported silica aerogels have a thermal conductivity as low as 15 mW/mK. The fragility of silica aerogels, however, makes them impractical for structural applications. The purpose of the study is to improve the ductility of aerogels while retain the low thermal conductivity of silica aerogels. We have established a new synthesis route, a 3-step sol-gel processing method. The method provides better control of the formation of aerogel structures. The produced silica aerogels show much improved ductility compared to conventional methods in literatures. Furthermore, the synthesized silica aerogels have thermal conductivities as low as about 9 mW/mK, which is the lowest in all reported solids. The ultra low thermal conductivity can be explained with nano-scale structures for the silica aerogels, which have been characterized using advanced techniques including BET and SEM. We have further investigated and demonstrated the ability of enhancing mechanical properties of silica aerogels through structure modification using the proposed 3-step sol-gel processing method. The molecular-level synergism between silica particles/clusters and the doped functional materials inverts the relative host-guest roles in the produced aerogel composite, leading to new stronger and more robust low-density materials.
Description
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 90-96).
Subjects
Mechanical Engineering.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
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