Papers by Keyword: Silica Aerogel

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Authors: J. Manohar, S. Ramprakash, G. Selvakumar, Dhiliban
Abstract: In this paper, a case study on replacing the existing insulating material (Mineral wool) by the Silica Aerogel in the main steam line (MSL) of the thermal power plant is presented.A sample length of 3 m in MSL was insulated with various thicknesses of silica aerogel, mineral wool and the combinations of mineral wool and silica aerogel. The heat loss in the sample length with different insulating material was calculated by carrying out field experiments. The results show that the silica aerogel is providing better insulation than the mineral wool. Nonetheless, the use of silica aerogel is expensive. To bring down the cost, hybrid insulation with the optimal thickness of silica aerogel + mineral wool + silica aerogel was suggested. This hybrid combination considerably reduced the heat loss and improved the thermal efficiency. The payback period for this implementation was reported.
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Authors: P.J. Reséndiz-Hernández, D.A. Cortés-Hernández, Juan Méndez Nonell, J.C. Escobedo-Bocardo
Abstract: Silica aerogels have attracted increasingly more attention due to their extraordinary properties and their existing and potential applications in a wide variety of technological areas. Materials that promote bone-tissue formation at their surface and bond to osseous tissues when implanted are called bioactive, such as pseudowollastonite particles. In this work, the synthesis of aerogels with pseudowollastonite particles was performed. The synthesis involved the preparation of an alcogel by a two step sol-gel route followed by ambient pressure drying. To promote a higher bioactivity the obtained aerogels were then biomimetically treated using simulated body fluids, SBF and 1.5 SBF. A high bioactivity was demonstrated by FT-IR, SEM, EDS, and XRD. The in vitro biocompatibility was assessed by testing cytotoxicity using rat osteoblasts cultures. The results obtained indicate that these materials are highly potential aerogels for bone tissue regeneration.
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Authors: Yasuyuki Nagashima, Toshio Hyodo, K. Fujiwara
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Authors: Hong Wei Li, Na Lv, Pan Yan Lu, Gang Qiang Geng, Wei Wang
Abstract: In this study, the powder of hydrophobic silica aerogel remaining nanopore by ambient pressure drying was successfully introduced into polystyrene beads during suspension polymerization. nanosilica powder without nanopore was also used. Pure polystyrene, silica aerogel/polystyrene (PS) and nanosilica/polystyrene beads were fabricated, respectively. The structure and properties of silica aerogel @PS composite beads were characterized by SEM, EDS, TG-DSC and FT-IR. The results of TG-DSC, FT-IR and EDS show silica aerogel is located in the PS beads, but it is difficult to be observed by SEM because of its low content. The introduction of silica and silica aerogel both decrease the transparency of PS beads. Silica aerogel loosen the microstructure of PS beads.
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Authors: Nor Suriani Sani, Nik Ahmad Nizam Nik Malek, Mohammed Rafiq Abdul Kadir, Halimaton Hamdan
Abstract: Hydroxyapatite (HA) modified silica aerogel (SA) was synthesized based on 2 different techniques namely encapsulation and in-situ via aqueous colloidal sol-gel process. The structure of the synthesized HA modified SA have been studied using Fourier transform infrared (FTIR) spectroscopy. FTIR spectra of HA modified SA, derived from in-situ technique appear to be different from those of encapsulation technique and free HA, with the main difference lying in the phosphate bending absorbance. Results showed that the encapsulation technique preserved the native confirmation of HA in SA frameworks compared to in-situ technique. It confirms that the use of an aqueous sol-gel encapsulation route provides a promising approach for the stabilization of HA in SA networks.
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Authors: Jaroslav Pokorný, Milena Pavlíková, Jaromír Žumár, Anton Trník, Zbyšek Pavlík
Abstract: Several thermal insulation systems were developed for improvement of thermal performance of buildings. Exterior thermal insulation systems represent usually natural solution of the problem of low thermal resistance of building envelopes. However, in some cases, there is necessary to realize interior thermal insulation systems, what brings number of possible problems. Their common disadvantage is a limitation of interior space due to the thickness of thermal insulation layer and a possible condensation of water vapor which permeates the thermal insulation system. On this account, new sandwich composite with silica aerogel originally designed for application in interior thermal insulation systems is studied in the paper. Thermal properties are measured by two transient methods using devices ISOMET 2114 and RTB. The water vapor transport parameters are determined on the basis of dry cup and wet cup methods. The obtained data gives information on thermal and water vapor transport properties of the particular layers of sandwich composite and predetermines its behavior at real climatic exposure of building.
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Authors: Tao Tao Zhang, Jing Huang, Rui Zhi Zhang, Peng Yan Mao, Pan Fang
Abstract: We study the preparation of thin film on the glass substrate with the method of dip coating, which is based on methanol and MTMS as raw materials, making them form silica aerogel by sol-gel method. Scanning electron micrographs (SEM) show that such a film possesses a porous three-dimensional network structure. The high porosity and low refractive index determine that the transmittance rate can reach 90%. The prepared film also exhibited apparent hydrophobic effect, with the contact angle of 156.3°and rolling angle of less than 10°. The transparency and superhydrophobic of the film make it suitable as multifunctional coatings for many application fields including solar cells, cellphones and a variety of electron device.
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Authors: Norkhairunnisa Mazlan, Norasiah Termazi, Suraya Abdul Rashid, Saeed Rahmanian
Abstract: Growing of carbon nanotubes (CNT) on the surface of highly porous silica aerogel offers a means to tailor the mechanical properties between fiber and matrix interface of a composite. The growth of CNT on the silica aerogel surface was done using chemical vapour deposition (CVD) technique. In this study, the morphology of the produced CNT was investigated by Scanning Electron Microscope (SEM) for confirmation of CNT existence. The composite were then prepared by shear mixing technique. Flexural strength of the CNT-SilAe/Epoxy nanocomposite were assessed as a function of CNT-SilAe concentration and dispersion in epoxy matrix. The flexural modulus and strength of epoxy composite increased significantly with inclusion of CNT-SilAe. The optimum loading of CNT-SilAe in epoxy composites was attained at 2 wt%, where the improvement in flexural strength and modulus were 8% and 11%, respectively.
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