Aerogel-aerogel composites for normal temperature range thermal insulations

摘要

Aerogel-aerogel composites are prepared by embedding highly insulating granular silica aerogel (1-2 mm, 5-58 vol.%) into ambient pressure dried resorcinol-formaldehyde (RF) aerogel. The organic RF aerogel matrix is synthesized via a sol-gel reaction of resorcinol (1,3-dihydroxybenzene) and formaldehyde in deionized water with Na2CO3 as the catalyst. Plates around 90 x 195 mm(2) with a thickness of 19-25 mm are obtained and can be processed for application by sawing and grinding. A theoretical model for the volume-based surface area was used to show that the matrix aerogel around the silica aerogel grains is affected by their presence. Composites have a density 0.19 <= rho <= 0.27 g/cm(3) and a thermal conductivity at room temperature between 0.026 and 0.053 W/mK. Composites can be used as thermal insulation material in a normal temperature range < 200 degrees C due to the decomposition of the organic phase above 200 degrees C. (C) 2016 Elsevier B.V. All rights reserved.