Apple pectin improves the mechanical characteristics
It is true that the structural elements linking the silicate nanoparticles are exceptionally fine and delicate, as electron microscope imaging shows. For this reason, Empa scientist Matthias Koebel, together with colleagues from the MINES ParisTech university, took on the challenge of bettering the mechanical characteristics of aerogels, following a path which has seldom before been trodden. The researchers created a novel class of materials by combining a silicate based aerogel with the biopolymer pectin (which occurs in apples, for example). The newly developed product demonstrated markedly improved mechanical properties the hybrid aerogel can be compressed to 80% of its original volume without breaking, an ability which the developers ascribe to the morphology of the pectin-silicate network. In the hybrid structure the nanoparticles are linked by more robust cross-elements than those in classical aerogels. In addition, as a result of this gain in mechanical resistance the tendency to create dust is minimized.
The decisive factor is, however, that depending on the pectin content the thermal conductivity of the hybrid material remains between 14 und 17 mWm-1K-1, which is only slightly poorer than that of classic aerogels. With their innovative development the scientists have killed not merely two but three birds with one stone! The hybrid aerogel is mechanically robust, an outstanding insulator and is manufactured from raw materials of biological and mineral origin. On top of all this, the project team has developed an environmentally-friendly manufacturing process for the hybrid aerogels based on an aqueous solution. In a recently published paper in the scientific journal «Angewandte Chemie» (http://dx.doi.org/10.1002/ange.201507328), the developers offer the prospect of being able to manufacture and use any required quantity of the novel aerogel on an industrial scale.