New thermal superinsulating materials from pectin based bio-aerogels
Résumé
Highly porous nanostructured materials are of great interest for thermal superinsulation. Silica aerogels have thermal conductivity lower than that of the air: 0.015 vs 0.025 W/(m.K). However, they are extremely fragile which hinders their extensive applications. Polysaccharide-based aerogels, or “bio-aerogels”, are a new generation of aerogels. For example, pectin, waste from food industry, forms gels in aqueous solution. Coagulation and drying with supercritical CO2 give nanostructured ultralight materials. They show very low densities (0.05-0.08 g/cm3), high specific surface areas (300 m²/g) and thermal conductivities of 0.02 W/(m.K). Organic-inorganic pectin-silica aerogels have even lower thermal conductivity. The morphology, thermal and mechanical properties of the new aerogels will be discussed.