Preparation of silica aerogels with improved mechanical properties and extremely low thermal conductivities through modified sol-gel process

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.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2010

Author dc:creator

• Zuo, Yanjia

Advisor dc:contributor.advisor

• Taofang Zeng and Gang Chen.

• Mechanical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/64600

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/64600