Study of the suitability of silica based xerogels synthesized using ethyltrimethoxysilane and/or methyltrimethoxysilane precursors for aerospace applications

Ochoa, M. Nieves Corella; Durães, Luísa; Beja, Α. Matos; Portugal, António

doi:10.1007/s10971-011-2604-7

Cited by 58 publications

(25 citation statements)

References 15 publications

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“…Silica based xerogels and aerogels were prepared following the sol-gel procedures described by Rao, Bhaghat and co-workers 2 5 and previously used by the authors, [8][9][10] but making some variations on the drying conditions. MTMS (CH 3 Si(OCH 3 3 , 98%, Aldrich), methanol (CH 3 OH, 99.8%, Riedel-de Haën), oxalic acid (C 2 H 2 O 4 , 99%, Fluka) and ammonium hydroxide (NH 4 OH, 25% in water, Fluka) were used as precursor, solvent, acid catalyst and basic catalyst, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…[8][9][10] The implemented drying methods were atmospheric pressure drying (APD), to produce the xerogels, and supercritical fluids drying (SFD), to obtain the aerogels. Besides the drying method, the drying conditions were varied-three different temperature cycles were used in APD and two heating rates were tested in SFD-in order to evaluate the conditions that minimize the gels' shrinkage.…”

Section: Introductionmentioning

confidence: 99%

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Effect of the Drying Conditions on the Microstructure of Silica Based Xerogels and Aerogels

Durães

Ochoa²,

Rocha³

et al. 2012

j nanosci nanotechnol

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Nanostructured silica based xerogels and aerogels are prepared by sol-gel technology, using methyltrimethoxysilane as precursor. The influence of the drying method and conditions on the microstructure of the obtained materials is investigated, since the drying stage has a critical influence on their porosity. Two types of drying methods were used: atmospheric pressure drying (evaporative), to produce xerogels, and supercritical fluids drying, to obtain aerogels. Although the supercritical fluids drying technique is more expensive and hazardous than the atmospheric pressure drying, it is well known that aerogels are less dense than the xerogels due to less pore shrinkage. However, the ideal situation would be to use atmospheric pressure drying in conditions that minimize the pore collapse. Therefore, in this work, different temperature cycles for atmospheric pressure drying and two heating rates for the supercritical fluids drying are tested to study the gels' shrinkage by analyzing the density and porosity properties of the final materials. The best materials obtained are aerogels dried with the lower heating rate (approximately 80 degrees C/h), since they exhibit very low bulk density (approximately 50 kg/m3), high porosity (95%)-mainly micro and mesopores, high surface area (approximately 500 m2/g), moderate flexibility and a remarkable hydrophobic character (>140 degrees). It was proved that the temperature cycles of atmospheric pressure drying can be tuned to obtain xerogels with properties comparable to those of aerogels, having a bulk density only approximately15 kg/m3 higher. All the synthesized materials fulfill the requirements for application as insulators in Space environments.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of the Drying Conditions on the Microstructure of Silica Based Xerogels and Aerogels

Durães

Ochoa²,

Rocha³

et al. 2012

j nanosci nanotechnol

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show abstract

“…Due to the insulation character of these materials, the thermal degradation of alkyl groups frequently occurs in two stages, first in the more superficial groups and then extended to the more inner groups [15]. All the aerogels lose less than 5% of their mass (except sample A-PEG that loses 6.5 wt%) until ∼500 • C, revealing high thermal stability of all the organically modified networks.…”

Section: Tgamentioning

confidence: 99%

Effect of additives on the properties of silica based aerogels synthesized from methyltrimethoxysilane (MTMS)

Durães

Maia

Portugal

2015

The Journal of Supercritical Fluids

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“…From the wide-angle XRD pattern (Fig. 2b), only a big diffraction peak at theta = 22 • was observed, which is associated with the spacing of Si atoms and angle of the group Si-O-Si [18]. In addition, no apparent diffraction peak can be observed in the small-angle XRD pattern (inset in Fig.…”

Section: Resultsmentioning

confidence: 94%

Preparation of silica aerogels using CTAB/SDS as template and their efficient adsorption

Zhuo

et al. 2015

Applied Surface Science

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Study of the suitability of silica based xerogels synthesized using ethyltrimethoxysilane and/or methyltrimethoxysilane precursors for aerospace applications

Cited by 58 publications

References 15 publications

Effect of the Drying Conditions on the Microstructure of Silica Based Xerogels and Aerogels

Effect of the Drying Conditions on the Microstructure of Silica Based Xerogels and Aerogels

Effect of additives on the properties of silica based aerogels synthesized from methyltrimethoxysilane (MTMS)

Preparation of silica aerogels using CTAB/SDS as template and their efficient adsorption

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