Microstructural and physical properties of the ambient pressure dried hydrophobic silica aerogels with various solvent mixtures

Rao, A. Parvathy; Rao, A. Venkateswara

doi:10.1016/j.jnoncrysol.2007.07.021

Cited by 32 publications

(6 citation statements)

References 32 publications

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“… 47 Meanwhile, in the APD process, the capillary force ( P r ) was unavoidable when hexane within the pores was replaced by air: causing the collapse of three-dimensional network. 48 For a certain pore and solvent, P r was definite and was exerted on the pore simultaneously with the solvent evaporation. This force usually resulted in the shrinkage and even collapse of the pore.…”

Section: Resultsmentioning

confidence: 99%

Organic–inorganic hybridization for the synthesis of robust in situ hydrophobic polypropylsilsesquioxane aerogels with fast oil absorption properties

Zhang

et al. 2018

RSC Adv.

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Section: Resultsmentioning

confidence: 99%

Organic–inorganic hybridization for the synthesis of robust in situ hydrophobic polypropylsilsesquioxane aerogels with fast oil absorption properties

Zhang

et al. 2018

RSC Adv.

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“…BET (Brunauer-Emmet-Teller) specific surface area of 570 m 2 /g was obtained by N 2sorption technique. Porosity, pore volume and pore size were calculated using formulae reported elsewhere [5,6,7]. Porosity of 96% was obtained for a mean tap density of 0.1 g/cm 3 .…”

Section: ∆P = -2 σ LV Cosθ R ⁄ Pmentioning

confidence: 99%

Hydrophobic Silica Aerogels by Ambient Pressure Drying

Nagapriya

Ajith

Sreemoolanadhan

et al. 2015

MSF

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Silica aerogels have been prepared through sol-gel process by polymerization of TEOS in the presence of NH4F and NH4OH as catalysts. The solvent present in the gel is replaced by ethanol followed by a non-polar solvent such as n-hexane prior to solvent modification step. Gels are made hydrophobic by treating them with HMDZ to prevent rupture during drying, which has been confirmed by FTIR. Gels are then washed and dried carefully in a PID controlled oven at atmospheric pressure. The ageing duration and solvent exchange combinations are optimized to yield crack-free gels prior to drying. Aerogels are characterized for density, specific surface area, pore volume, pore size, thermal stability and contact angle. Hydrophobic, high surface area (570 m2/g), low density (0.07 g/cm3) silica aerogels are synthesized by using optimized mole ratio of precursors and catalysts. Silica aerogel granules (1-3 mm) as well as monoliths (Ф~35 mm) could be produced through ambient pressure drying of gels.

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“…Silica aerogel is an ideal porous material with a pearl necklace-like three-dimensional structure having interstitial mesopores. Such structural feature makes it possible to use it as an insulator because it shows low density and low thermal conductivity due to high porosity with 90% or more of air [23][24][25][26]. Silica aerogel as an insulating material has a thermal conductivity of 20 mW/mK or less, and has even smaller thermal conductivity than other conventional insulating materials.…”

Section: Introductionmentioning

confidence: 99%

Preparation and Properties of Polyurethane Composite Foams with Silica-Based Fillers

Lee

Jeon

et al. 2022

Applied Sciences

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Polyurethane composite foams were prepared by adding three different types of silica materials as a filler to improve the mechanical and thermal insulation properties. The first type of filler consists of silica aerogels with high-volume pores, with the expectation of improving the thermal insulation of PU foams because silica aerogel itself has superior thermal insulation properties. Silica nanoparticle is used for the second type that has a size very similar to the pore size of silica aerogels for comparison. The last type to produce polyurethane composite foam uses a sol–gel reaction to produce polysiloxane that reacts with polyols during the urethane reaction and forming process. In particular, in the case of silica aerogels and nanoparticles, their surfaces are modified with APTES and then polymeric methylene diphenylene diisocyanate (PMDI) to increase the interaction between the polymer matrix and inorganic fillers. The polyurethane foam structure was successfully produced in all cases of composite foams. As expected, the mechanical properties and the thermal insulation effect were enhanced by the addition of silica fillers, but found to be closely related to the cell structure of polyurethane foams. The addition of small amounts of inorganic fillers improves the mechanical and thermal properties, but the higher the amount of filler, the worse they are due to the agglomeration of fillers on the cell walls. The dispersion of added inorganic fillers within the foam cells should be controlled effectively. Surface-modified silica fillers exhibit better enhancement of mechanical and thermal insulation properties.

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Microstructural and physical properties of the ambient pressure dried hydrophobic silica aerogels with various solvent mixtures

Cited by 32 publications

References 32 publications

Organic–inorganic hybridization for the synthesis of robust in situ hydrophobic polypropylsilsesquioxane aerogels with fast oil absorption properties

Organic–inorganic hybridization for the synthesis of robust in situ hydrophobic polypropylsilsesquioxane aerogels with fast oil absorption properties

Hydrophobic Silica Aerogels by Ambient Pressure Drying

Preparation and Properties of Polyurethane Composite Foams with Silica-Based Fillers

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