Hydrophobic and low density silica aerogels dried at ambient pressure using TEOS precursor

2009 ◽  
Vol 471 (1-2) ◽  
pp. 296-302 ◽  
Author(s):  
Jyoti L. Gurav ◽  
A. Venkateswara Rao ◽  
Uzma K.H. Bangi
Keyword(s):  
Ambient Pressure ◽  
Silica Aerogels ◽  
Low Density

Super Thermal Insulating SiO2 Cryogels Prepared by Vacuum Freeze Drying

2010 ◽  
Vol 105-106 ◽  
pp. 851-854 ◽  
Author(s):  
Li Fen Su ◽  
Lei Miao ◽  
Gang Xu ◽  
Sakae Tanemura
Keyword(s):  
Freeze Drying ◽  
Ambient Pressure ◽  
Supercritical Drying ◽  
Silica Aerogels ◽  
Base Catalysis ◽  
Low Density ◽  
Solvent Exchange ◽  
Acid Base ◽  
Thermal Insulating ◽  
Silica Precursor

Traditionally, silica aerogels with low thermal conductivity are prepared by supercritical drying, however, the process is expensive and hazardous due to it run in autoclaves. In order to overcome these disadvantages, a cheaper and safer process, drying at ambient pressure has been developed for decades, but tedious repetitive gel washing and solvent exchange steps are involved. Therefore, in the present study, a novel vacuum freeze-drying was utilized to prepare the super thermal insulating SiO2 cryogels. The wet gels were synthesized via acid-base catalysis using tetraethoxysilane (TEOS) as a silica precursor and ethanol as a solvent. After vacuum freeze drying, nanoporous SiO2 cryogels with low density in the range of 0.08-0.15 g/cm3 were obtained.

Study on Preparation of Mesoporous Silica Aerogels with Low Density and High Properties via Ambient Pressure Drying

2010 ◽  
Vol 148-149 ◽  
pp. 1491-1496
Author(s):  
Gang Qiang Geng ◽  
Wei Tao Bi ◽  
Yu Zhang ◽  
Deng Ke Sun
Keyword(s):  
Mesoporous Silica ◽  
Ambient Pressure ◽  
Sol Gel ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Ethanol Solution ◽  
Low Density ◽  
Micro Structure ◽  
Gel Time

The SiO2 aerogels of low density was fabricated by ion exchange and sol-gel method on the basis of sodium silicate. The effect of pH, aging，addition of DCCA and annealed temperature on the gel time, aerogel density, porosity and the micro-structure was systemly studied. The results showed that when the pH is 5, aging was 30%Vol .of TEOS/ethanol solution ,the addition of DCCA was 1.5ml, the gel system was annealed at 50 for 84 h, 60 for 72h, the best quality of silica aerogels with low density (0.14g/cm3), higher specific surface(610.643 m2/g) and pore size of 20~40 nm can be obtained.

Highly flexible silica aerogels derived from methyltriethoxysilane and polydimethylsiloxane

2015 ◽  
Vol 39 (10) ◽  
pp. 7832-7838 ◽  
Author(s):  
Liang Zhong ◽  
Xiaohong Chen ◽  
Huaihe Song ◽  
Kang Guo ◽  
Zijun Hu
Keyword(s):  
Ambient Pressure ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Low Density ◽  
Rapid Synthesis ◽  
Hydrophobic Silica ◽  
Highly Hydrophobic

The rapid synthesis of low-density, highly hydrophobic silica aerogels was performedviaambient pressure drying.

Low-density TEOS-based silica aerogels prepared at ambient pressure using isopropanol as the preparative solvent

2009 ◽  
Vol 487 (1-2) ◽  
pp. 744-750 ◽  
Author(s):  
Askwar Hilonga ◽  
Jong-Kil Kim ◽  
Pradip B. Sarawade ◽  
Hee Taik Kim
Keyword(s):  
Ambient Pressure ◽  
Silica Aerogels ◽  
Low Density

Effect of ambient pressure on low-density nozzle plumes

1995 ◽  
Author(s):  
Chan-Hong Chung ◽  
Kenneth D ◽  
Robert Stubbs
Keyword(s):  
Ambient Pressure ◽  
Low Density

NMR studies of superfluid in low density silica aerogels

2003 ◽  
Vol 329-333 ◽  
pp. 292-295
Author(s):  
J.E. Baumgardner ◽  
L.V. Polukhina ◽  
Y. Lee ◽  
J.F. Poco ◽  
L.W. Hrubesh ◽  
...  
Keyword(s):  
Silica Aerogels ◽  
Low Density ◽  
Nmr Studies

scholarly journals Silica Aerogel Monoliths Derived from Silica Hydrosol with Various Surfactants

Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3192 ◽  
Author(s):  
Dong Chen ◽  
Xiaodong Wang ◽  
Wenhui Ding ◽  
Wenbing Zou ◽  
Qiong Zhu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Stability ◽  
Silica Aerogel ◽  
Low Cost ◽  
Ambient Pressure ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Low Thermal Conductivity ◽  
Silica Hydrosol ◽  
High Production Cost

Owing to their ultra-low thermal conductivity, silica aerogels are promising thermal insulators; however, their extensive application is limited by their high production cost. Thus, scientists have started to explore low-cost and easy preparation processes of silica aerogels. In this work, a low-cost method was proposed to prepare silica aerogels with industrial silica hydrosol and a subsequent ambient pressure drying (APD) process. Various surfactants (cationic, amphoteric, or anionic) were added to avoid solvent exchange and surface modification during the APD process. The effects of various surfactants on the microstructure, thermal conductivity, and thermal stability of the silica aerogels were studied. The results showed that the silica aerogels prepared with a cationic or anionic surfactant have better thermal stability than that prepared with an amphoteric surfactant. After being heated at 600 °C, the silica aerogel prepared with a cationic surfactant showed the highest specific surface area of 131 m2∙g−1 and the lowest thermal conductivity of 0.038 W∙m−1∙K−1. The obtained low-cost silica aerogel with low thermal conductivity could be widely applied as a thermal insulator for building and industrial energy-saving applications.

Sign in / Sign up

Export Citation Format

Share Document