Thermal assessment of ambient pressure dried silica aerogel composite boards at laboratory and field scale

The article presents the synthesis of silica aerogel from a much cheaper precursor of water glass that was reinforced with short pitch carbon fiber by way of ambient pressure drying. Before being added to the silica gel, the carbon fibers were surface modified to increase adhesion at the interfacial border. We were able to obtain stable structures of the composite with the amount of fibers above 10% by volume. The presence of fibers in the silica matrix resulted in lower synthesis time of the composite, improved adhesion of fibers to the aerogel nanostructure, and increased mechanical and structural parameters. An additional effect of the presence of fibers in excess of 10% by volume was a new function of the nanocomposite—the ability to conduct electric current. The most optimal parameters of the composite, however, were obtained for silica aerogel reinforced with 10 vol.% of carbon fibers. This material indicated relatively low density and good physical parameters. The paper also analyzes the results on the synthesis of fiber-reinforced silica aerogels that have appeared in recent years and compares these to the results gained in presented work.

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Environmental microscopy of capillary stress-induced strain behavior in ambient-pressure aerogels

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100166713 ◽

1996 ◽

Vol 54 ◽

pp. 850-851

Author(s):

Sudeep M. Rao ◽

Joshua Samuel ◽

Sai S. Prakash ◽

C. Jeffrey Brinker

Keyword(s):

Silica Aerogel ◽

Ambient Pressure ◽

Drying Shrinkage ◽

Pore Filling ◽

Silica Network ◽

Strain Behavior ◽

Partially Saturated ◽

Capillary Stress ◽

Wetting Liquid ◽

Aerogel Films

Ambient pressure silica aerogel thin films have recently been prepared by exploiting reversible drying shrinkage caused by derivatization of the internal gel surface. Aerogels have porosities of upto 99.9% and due to the small size of the pores (few nanometers), large capillary stresses are produced in gels that are partially saturated with a wetting liquid. As a result of these capillary stresses, the flexible silica network undergoes strain which has been observed using environmental microscopy. This technique allows variation of the equilibrium vapor pressure and temperature, and a simultaneous monitoring of the deformation of the unconstrained film thickness. We have observed >600% deformation during the pore-filling and pore-emptying cycles. In this presentation, we discuss the unique stress-strain behavior of these films.Ref.: Sai S. Prakash, C. Jeffrey Brinker, Alan J. Hurd & Sudeep M. Rao, "Silica aerogel films prepared at ambient pressure by using surface derivatization to induce reversible drying shrinkage", Nature. Vol. 374, 30 March, 1995, 439-443.

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Preparation of hydrophobic silica aerogel with kaolin dried at ambient pressure

Colloids and Surfaces A Physicochemical and Engineering Aspects ◽

10.1016/j.colsurfa.2016.04.059 ◽

2016 ◽

Vol 501 ◽

pp. 83-91 ◽

Cited By ~ 26

Author(s):

Wenbin Hu ◽

Mengmeng Li ◽

Wei Chen ◽

Ning Zhang ◽

Bo Li ◽

...

Keyword(s):

Silica Aerogel ◽

Ambient Pressure ◽

Hydrophobic Silica

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Polypropylene/Silica Aerogel Composite Incorporating a Conformal Coating of Methyltrimethoxysilane-Based Aerogel

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2019.16257 ◽

2019 ◽

Vol 19 (3) ◽

pp. 1376-1381 ◽

Cited By ~ 4

Author(s):

Haryeong Choi ◽

Vinayak G Parale ◽

Kyu-Yeon Lee ◽

Ha-Yoon Nah ◽

Zied Driss ◽

...

Keyword(s):

Silica Aerogel ◽

Conformal Coating ◽

Aerogel Composite

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Silica Aerogel Monoliths Derived from Silica Hydrosol with Various Surfactants

Molecules ◽

10.3390/molecules23123192 ◽

2018 ◽

Vol 23 (12) ◽

pp. 3192 ◽

Cited By ~ 3

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.

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EFFECT of IONIC LIQUID CONTENT on MONOLITHIC STRUCTURE of AMINE-MEDIATED SILICA AEROGEL via AMBIENT PRESSURE DRYING

Journal of the Turkish Chemical Society Section A Chemistry ◽

10.18596/jotcsa.390372 ◽

2018 ◽

pp. 663-678

Author(s):

Nilay Gizli ◽

Selay SERT ÇOK ◽

Fatoş KOÇ

Keyword(s):

Ionic Liquid ◽

Silica Aerogel ◽

Ambient Pressure ◽

Ambient Pressure Drying ◽

Liquid Content ◽

Monolithic Structure

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Thermal Radiation in Silica Aerogel and its Composite Insulation Materials

Volume 10: Heat and Mass Transport Processes, Parts A and B ◽

10.1115/imece2011-62632 ◽

2011 ◽

Author(s):

Gaosheng Wei ◽

Yusong Liu ◽

Xinxin Zhang ◽

Xiaoze Du

Keyword(s):

Thermal Radiation ◽

Extinction Coefficient ◽

Silica Aerogel ◽

Extinction Coefficients ◽

Ceramic Fibre ◽

Insulation Materials ◽

Hot Strip ◽

Aerogel Composite ◽

Infrared Spectrometer ◽

Spectral Extinction Coefficient

This paper engages in experimental measurements on thermal radiative transfer in silica aerogel and its composite insulation materials (xonotlite-aerogel composite and ceramic fibre-aerogel composite). The samples of silica aerogel, xonotlite-type calcium silicate, and ceramic fibre insulation materials are all considered as a semi-transparent medium capable of absorbing, emitting and scattering thermal radiation. The spectral transmittances are then measured at different infrared wavelengths ranging from 2.5 to 25μm with a Fourier transform infrared spectrometer (FTIR), and subsequently used to determine the specific spectral extinction coefficient and the specific Rossland mean extinction coefficient of the sample. The radiative conductivities deduced from the overall thermal conductivities measured with the transient hot-strip (THS) method are compared with the predictions from the diffusion approximation by using the measured spectral extinction coefficient. The results show that the spectral extinction coefficients of the samples are strongly dependent on the wavelength, particularly in the short wavelength regime (<10μm). The total Rossland mean extinction coefficients of the samples are all decreasing with the temperature increasing. The radiative conductivities are found almost proportional to the cubic temperature, and decreases as the sample density increases.

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