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Composite silica aerogels were prepared using sodium silicate and ceramics fibers. The thermal conductivities of these composites were investigated to determine how effective they would be as thermal insulation. As temperature increased to 400oC, the thermal conductivity of these composites only increased from 0.0266 to 0.0572 W/(m·K). This indicates that these composites which have good structural and mechanical properties would be good thermal insulators during thermal processes....
A variety of tannin-formaldehyde aerogels were produced in order to examine the effects of pH and dilution during their manufacture. The authors produced a phase diagram that could describe them. Extensive physical property characterization was performed on the sample aerogels, including porosity, thermal conductivity, volume shrinkage, BET surface area and microscopic texture. Conditions under which the highest surface area and pore volumes were produced were identified. The TPS instrument was ...
Ultralow density silica aerogels were formulated by sol-gel process using tetramethyl orthosilicate as the precursor. A supercritical drying step was performed using acetonitrile solvent extraction. These aerogels were found to have a high specific surface area (~812m2/g) and they were found to be excellent thermal insulators with thermal conductivities ranging from 0.024 to 0.043 W/m K at temperatures up to 400oC....
The authors present a method of increasing the structural stability of silica aerogels by producing flexible aerogel composites by electrospinning and sol-gel processing. Three composites, each reinforced with one of three different polyvinylidene fluoride (PVDF) microstructures, were prepared in order to determine the effects of these microstructures on the mechanical and thermal properties of the composites. It was found that the compressive strength and flexibility of the composites were significantly ...
This paper proposes conducting carbon aerogels, composed of graphene and multi-walled carbon nanotubes, as an option for a thermoelectric material. The researchers found that this combination of materials increased the electrical conductivity and the Seebeck coefficient due to bridging effects, and decreased the thermal conductivity through high porosity and a uniquely structured 3-D skeleton. Atomic force microscopy and X-ray diffraction were used to quantify the physical structure of the aerogels. ...