Preparation of Monolithic Silica Aerogel of Low Thermal Conductivity by Ambient Pressure Drying

Journal of the American Ceramic Society - Tập 90 Số 7 - Trang 2003-2007 - 2007
Te‐Yu Wei1, Tso‐Fu Mark Chang1, Shih‐Yuan Lu1, Yu‐Cheng Chang2
1Department of Chemical Engineering, National Tsing Hua University, Hsin‐Chu 30043, Taiwan
2Combustion Application Laboratory, Industrial Energy Conservation Technology Division, Energy & Environment Research Laboratories, Industrial Technology Research Institute, Hsin‐Chu 310, Taiwan

Tóm tắt

Monolithic silica aerogels with thermal conductivity as low as 0.036 W·(m·K)−1 and porosity as high as 97% were successfully prepared by ambient pressure drying through a multiple modification approach. This approach may replace the more costly and dangerous operation of supercritical drying. The tetraethoxysilane (TEOS)‐derived wet gel was made hydrophobic with multiple treatments of trimethylchlorosilane and dried under ambient pressure. The multiple treatments were found to be necessary to achieve sufficient modification of the wet gel for reduction in drying‐induced surface tension force to maintain product integrity and high porosity. Comparisons in nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy for surface bonding and contact angle measurement for hydrophobicity between the no, single, and multiple surface modification (MSM) samples were conducted to reveal the difference in the extent of the resulting surface modification. In conclusion, the MSM procedure reduced the volume shrinkage, increased the monolithicity and porosity, and lowered the thermal conductivity of the resulting aerogels.

Từ khóa


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Thông tin xuất bản

Journal of the American Ceramic Society

Tập 90 Số 7

2003-2007

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