Comparison of some physico-chemical properties of hydrophilic and hydrophobic silica aerogels

Wagh, P. B.; Ingale, S. V.

doi:10.1016/s0272-8842(01)00056-6

Cited by 77 publications

(37 citation statements)

References 11 publications

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“…The slope of the curve, however, is different in the temperature ranges from 900 Figure 3 FTIR spectra of silica xerogel loaded by 5 mol% SnO 2 and sintered at different temperatures Figure 3 shows the Fourier Transform Infra-Red (FTIR) spectra of SX loaded by 5 mol% SnO 2 and sintered at different temperatures. For all samples, the absorption band (peak 1) observed at about 464 cm -1 was attributed to an Si-O-Si bending vibration (Wagh & Ingale, 2002). Peak 2, which appears at 634 cm −1 , relates to the O-Sn-O bridge functional groups of SnO 2 (Tan et al, 2011) which occur in samples sintered at temperatures greater than or equal to 900 o C. This confirms the presence of SnO 2 as a crystalline phase, and is in agreement with the results of the XRD analysis.…”

Section: Resultsmentioning

confidence: 93%

“…For all samples, bands at 802 cm -1 (peak 3) and 1099 cm -1 (peak 5) are assigned, respectively, to the symmetric stretching of the Si-O-Si group and to the asymmetric stretching of the Si-O-Si structural bond of siloxane (Jung et al, 2005). In an untreated sample, peak 4 at around 980 cm -1 corresponds to the presence of an Si-OH group (Wagh & Ingale, 2002). Peak 6, observed at 1620 cm -1 , is associated with bending H-O-H bond groups of adsorbed water molecules, while a broad band (peak 7) at 3452 cm -1 is attributed to O-H stretching from hydroxyl groups that are present on the surface of the material (Yang & Gao, 2006).…”

Section: Resultsmentioning

confidence: 98%

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Densification Behavior of SnO2-Glass Composites Developed from the Incorporate of Silica Xerogeland SnO2

Aripin¹,

Mitsudo²,

Sudiana³

et al. 2016

IJTech

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In this investigation, SnO 2 -glass composites were produced by mixing SnO 2 and amorphous silica xerogel (SX) extracted from sago waste ash. The composition was prepared by adding 5 mol% of SnO 2 into SX; the samples were dry pressed and sintered in a temperature range between room temperature and 1500 o C. Their properties were characterized on the basis of the experimental data obtained using Archimedes' principle, X-ray diffraction (XRD), Fourier transformed infra-red (FTIR), and a scanning electron microscopy (SEM). It was found that the bulk density increased along with the sintering temperature. In the temperature range from 1300 o C to 1500 o C, the glass ceramic reached a bulk density of about 2.5 g/cm 3 . The results of the interpretation of XRD patterns, FTIR spectra, and SEM images allow us to conclude that this increase in density was due to an increased degree of crystallinity of SnO 2 in the silica xerogel composite.

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Section: Resultsmentioning

confidence: 93%

Section: Resultsmentioning

confidence: 98%

Densification Behavior of SnO2-Glass Composites Developed from the Incorporate of Silica Xerogeland SnO2

Aripin¹,

Mitsudo²,

Sudiana³

et al. 2016

IJTech

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“…Figure 5a shows the FTIR spectra of silica xerogel with varying loading of TiO 2 sintered at 1200°C. For all samples, the absorption bands (peaks 1, 2, and 3) observed at about 464 cm −1 , 800 cm −1 , and 624 cm −1 were attributed to a Si-O-Si bending vibration, the symmetric stretching mode of the Si-O-Si bond, and the crystalline cristobalite phase, respectively (Wagh & Ingale, 2002;Yang & Gao, 2006). Additionally, for all samples, peak 4, at around 952 cm −1 , corresponds to the presence of Si-O-Ti vibration modes, due to the overlapping of the vibration of Si-OH and Si-O-Ti bonds (El-Toni et al, 2006;Balachandaran et al, 2010).…”

Section: Resultsmentioning

confidence: 95%

Formation and Particle Growth of TiO2 in Silica Xerogel Glass Ceramic During a Sintering Process

Aripin¹,

Made²,

Mitsudo³

et al. 2017

IJTech

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This investigation presents the synthesis procedure and the results of an investigation of the crystallite growth of TiO 2 and the formation of Si-O-Ti bonds in novel silica xerogel (SiO 2 ) glass ceramic produced from an amorphous SX derived from sago waste ash. The composition had been prepared by adding various amounts of TiO 2 , from 20 wt% to 80 wt%, into the amorphous SiO 2 , and then a series of samples were sintered at 1200°C for 2 hours. The influence of the content of TiO 2 and the sintering temperature on the properties of TiO 2 , namely crystallite size and formation of Si-O-Ti bonds, has been studied in detail. The properties of the produced ceramics have been characterized on the basis of the experimental data obtained using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. It has been found that an addition of SiO 2 confers an appreciable effect on the quantity of Si-O-Ti bonds. The interpretation of the XRD pattern allows one to explain the increase in the crystallite size of rutile TiO 2 by a decreased quantity of Si-O-Ti bonds.

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“…This type of aerogels have undergone a surface modification, which provides the hydrophobic character [32,41,43,54,61,63,68,69,72,74]. In particular, their contact angle with water droplet depends on the silylating agent (non-polar groups) [43,54,61,69].…”

Section: Introductionmentioning

confidence: 99%

“…In particular, their contact angle with water droplet depends on the silylating agent (non-polar groups) [43,54,61,69]. The data regarding water absorption of such aerogels shows that the untreated aerogels (hydrophilic) absorb water by 4-5 times their own weight, while silylated aerogels (hydrophobic), absorb less than 2 % water with respect to their own weight [68]. Nevertheless, the high hydrophobicity of aerogels poses a processing problem when mixed with water based mineral binders.…”

Section: Introductionmentioning

confidence: 99%

Anhydrite/aerogel composites for thermal insulation

et al. 2015

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High performance thermal insulating composite materials can be produced with mineral binders and hydrophobic aerogel particles through a hydrophilization process for the latter with surfactants. The present study is focused on the development of aerogel/calcium sulfate composites by the hydrophilization of hydrophobic silica aerogel particles through a polymer-based surfactant. Its effects on the microstructure and hydration degree are examined as well as their relation to the resulting mechanical and physical properties. Results show that composites with an around 60 % of aerogel by volume can achieve a thermal conductivity \30 mW/m 9 K. Interestingly, a surfactant addition of 0.1 % by wt% of the water in the mixtures provides better material properties compared to a surfactant wt% addition of 5 %. However, it has been found around 40 % entrained air, affecting the material properties by reducing the binder and aerogel volume fractions within the composites. Moreover, gypsum crystallization starts to be inhibited at aerogel volume fractions [35 %. Towards material optimization, a model for the calculation of thermal conductivity of composites and an equation for the compressive strength are proposed.

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Comparison of some physico-chemical properties of hydrophilic and hydrophobic silica aerogels

Cited by 77 publications

References 11 publications

Densification Behavior of SnO2-Glass Composites Developed from the Incorporate of Silica Xerogeland SnO2

Densification Behavior of SnO2-Glass Composites Developed from the Incorporate of Silica Xerogeland SnO2

Formation and Particle Growth of TiO2 in Silica Xerogel Glass Ceramic During a Sintering Process

Anhydrite/aerogel composites for thermal insulation

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