However, they are very brittle.
A flexible aerogel-based insulation material has been developed by Aspen Aerogels (the USA),
but it is much more expensive than conventional insulation materials [17].
To investigate the thermal insulation ability of our recycled cellulose aerogel, a thermal conductivity measurement was carried out with a C-Therm TCi Thermal Conductivity Analyzer System (Fig. 5a).