Hygro-thermal properties of silica aerogel blankets dried using microwave heating for building thermal insulation

Abstract

Silica aerogels are highly porous and open-cell materials made of amorphous silica nanoparticles, interconnected in a 3D random network. Silica aerogel-based materials have a great potential as thermal insulation in building thanks to their very low thermal conductivity. However, pure silica aerogels are fragile with low mechanical moduli. Making aerogel composite materials by combining fibers with a pre-gel mixture of a gel precursor or by impregnating a fiber network by such a mixture seems to be a promising way to enhance the mechanical properties of such materials. After drying, the resulting composite is called aerogel blanket. The aerogel blanket is mechanically strengthened, flexible and still has a very low thermal conductivity. Aerogel blankets are usually dried using supercritical process but it is considered as a main drawback for large scale industrialization. The present study uses an innovative micro wave drying. The purpose of this work is to analyze and characterize a handy, light, super-insulating aerogel blanket dried in ambient conditions and see if it could be suitable for building thermal insulation. Two types of blankets have been investigated: the first one with a glass fiber web and the second one with a PET (polyethylene terephthalate) fiber web. Hygro-thermal characterizations were done and show that the aerogel blankets have an excellent thermal conductivity (0.015Wm−1K−1) and a hydrophobic behavior. The studied aerogel blankets obtained using a new ambient drying process show practically the same characteristics as their counterpart dried with a supercritical process and mark a step forward in the aerogel blanket industrialization.