Structure and mechanical properties of silica aerogels and xerogels modeled by molecular dynamics simulation

Murillo, John S. Rivas; Bachlechner, Martina E.; Campo, F.A.; Barbero, Ever J.

doi:10.1016/j.jnoncrysol.2010.03.019

Cited by 82 publications

(114 citation statements)

References 33 publications

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“…These efforts largely concentrated on accurately reproducing the porous and fractal nature of silica aerogels [11][12][13][14][15][16][17] using various methods. In particular, Kieffer and Angell [11] attempted to use molecular dynamics (MD) simulation, together with an interaction potential of the Born-Mayer form, to gradually expand a well-thermalized sample of amorphous silica.…”

Section: Introductionmentioning

confidence: 99%

A molecular dynamics study of the thermal conductivity of nanoporous silica aerogel, obtained through negative pressure rupturing

Ng¹,

Yeo²

2012

Journal of Non-Crystalline Solids

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Section: Introductionmentioning

confidence: 99%

A molecular dynamics study of the thermal conductivity of nanoporous silica aerogel, obtained through negative pressure rupturing

Ng¹,

Yeo²

2012

Journal of Non-Crystalline Solids

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“…The fractal dimensions were determined and plotted in Fig. 4.18 in comparison with results from previous theoretical studies (Nakano et al 1994;Murillo et al 2010), where good agreement was obtained.…”

Section: Silica Aerogel With Tersoff Potentialmentioning

confidence: 64%

“…The same expansion scheme was employed by Nakano et al (1994) with the Vashishta interatomic potential (Vashishta et al 1990) to determine structural correlations such as the internal surface area, pore surface-to-volume ratio, pore-size distribution, fractal dimension, correlation length, and mean-particle size as a function of aerogel density. Subsequently, a different method of expanding, heating, and quenching dense amorphous silica was developed by Murillo et al (2010) to characterize the mechanical properties of silica aerogels. In comparison with experimental results, this method achieved a good fit for the elastic moduli but not the strength.…”

Section: Numerical Characterization Of Aerogel Structures and Propertiesmentioning

confidence: 99%

“…Appropriate MD models have been formulated by the authors (Ng et al 2012;Lei et al 2013;Yeo et al 2013) across a wide range of densities for fast and reasonable reproduction of the geometrical, mechanical, and thermal properties of bulk experimental porous silica aerogel. It will be demonstrated that differing methods of negative pressure rupturing first introduced by Kieffer and Angell (1988), as well as the heating, expanding, and quenching scheme first proposed by Murillo et al (2010), will result in dramatic variations in thermal conductivities obtained. These are modeled using the van Beest-Kramer-van Santen interatomic potential (van Beest et al 1990;Kramer et al 1991) and a re-parameterized Tersoff potential (Munetoh et al 2007), respectively.…”

Section: Numerical Characterization Of Aerogel Structures and Propertiesmentioning

confidence: 99%

“…The second method to generate porous silica is the expanding, heating, and quenching scheme of Murillo et al (2010). In this scheme, instantaneous expansion of the same initial β-cristobalite lattice configuration brings the system to the , and 0.32 g/cm 3 from left to right, respectively desired density, before it is heated and quenched from 3000 to 300 K over 350 ps to produce aerogels in the density range of 0.3-1.0 g/cm 3 .…”

Section: Numerical Generation Of Aerogel Structuresmentioning

confidence: 99%

See 2 more Smart Citations

Effects of Nanoporosity on the Mechanical Properties and Applications of Aerogels in Composite Structures

Joshi

Yeo

2016

Advances in Nanocomposites

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Aerogels are ultralight solids with nanoporous structure and are one of the world's lightest materials available in the market. It is a dry gel, principally made up of 99.8 % of air and weighing just around three times that of air. The first aerogels were realized in 1931, when Kistler (J Phys Chem 36: [52][53][54][55][56][57][58][59][60][61][62][63][64] 1932) attempted to remove liquid from a wet gel. It started out with the testing of the hypothesis that the liquid in a jelly can be replaced by a gas so as to avoid the collapse of the wet gel. He postulated that it was possible to slowly expand the supercritical fluid within a gel and obtain an air-filled non-collapsed gel structure. He subsequently succeeded in producing silica aerogels with densities in the range 20-100 kg/m 3 , as well as aerogels of alumina, tungsten, ferric, and stannic oxides. Today, silica aerogel is frequently used in nanocomposites for their light weight and excellent thermal insulating properties. In this chapter, we document some of the silica aerogel-filled carbon composite sandwich structures we have recently developed and also numerically examine the underlying mechanisms which enable silica aerogels to possess extreme insulation properties and especially how pore size plays a major role.

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Aerogel Spring‐Back Correlates with Strain Recovery: Effect of Silica Concentration and Aging

et al. 2021

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Silica aerogels display exceptional properties and great application potential, with a mature market in thermal insulation. Both supercritical drying (SCD) and ambient pressure drying (APD) routes are implemented industrially. Herein, how aging and silica content affect the mechanical properties, and how these in turn determine the shrinkage, spring back, and density during APD are systematically investigated. The APD densities display a U‐shaped dependence of density w.r.t. silica concentration. At low silica concentrations, the gels cannot withstand the capillary forces during APD and dense xerogels are obtained. At intermediate to high concentrations, APD shrinkage is strongly reduced and density increases with silica concentration. A series of cylinders are prepared by SCD and investigated by uniaxial compression and their strain recovery is determined systematically. The mechanical responses are plastic, viscoelastic, and brittle in nature for low, intermediate, and high silica concentrations, respectively. The strain recovery of the SCD cylinders correlates to the degree of spring back during APD. The viscoelastic response of SCD aerogels having 6 wt% corresponds to the silica concentration where a minimum in APD aerogel density is observed. The importance of gel mechanics for silica aerogel spring back during APD, in addition to surface modification and hydrophobization is highlighted.

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Structure and mechanical properties of silica aerogels and xerogels modeled by molecular dynamics simulation

Cited by 82 publications

References 33 publications

A molecular dynamics study of the thermal conductivity of nanoporous silica aerogel, obtained through negative pressure rupturing

A molecular dynamics study of the thermal conductivity of nanoporous silica aerogel, obtained through negative pressure rupturing

Effects of Nanoporosity on the Mechanical Properties and Applications of Aerogels in Composite Structures

Aerogel Spring‐Back Correlates with Strain Recovery: Effect of Silica Concentration and Aging

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