Ambient-Dried Superinsulating and Monolithic Silica-Based Aerogels via the Use of Short Cellulose Fibers

Abstract : Silica-based aerogels have been studied for many decades for thermal superinsulation applications. Commercial products exhibiting excellent thermal insulation properties are already available on the market but ambient-drying routes are still intensively studied in order to compete with supercritical drying and further reduce associated costs of production. One of the main issues concerns preservation of monolithicity of the wet gels via ambient-drying. Most known works were related to use of non-woven fibrous mats to produce so-called blankets. Additionally, recent studies have demonstrated that it is possible to obtain superinsulating silica-based monoliths by using Ormosils precursors at lab-scale [1]. Within the present study, we have demonstrated that it is also possible to maintain macroscopic cohesion of the silica phase by using short cellulosic fibers and still working with TEOS. These ambient-dried monolithic organic-inorganic composites present morphological, structural and thermal properties similar to those of their supercritical CO2 counterparts. The presence of fibers lead to a significant improvement of mechanical properties as shown by 3-points bending characterization. Compared to pure silica samples, brittle behavior disappears but more interesting, ambient-dried composites appear more ductile than the supercritically dried ones. Proof of concept was first demonstrated with reference cellulosic fibers (Tencel® product coming from Lyocel process). Then this lab-scale method was extended successfully to other cellulose based fibers such as wood and flax. Using different fiber geometries and concentrations as well as alternative fibers allowed us to achieve levels of thermal conductivity lower than 0.015 W/m.K in room conditions. We will present global processing route, materials properties, comparison with supercritical drying and effect of fiber concentration and length on the properties of the composites. [1] Hayase G, Kanamori K, Maeno A, Kaji H, Nakanishi K (2016) Dynamic spring-back behavior in evaporative drying of polymethylsilsesquioxane monolithic gels for low-density transparent thermal superinsulators, J Non-Cryst Solids 434:115-119
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Communication dans un congrès
Materials Research Society (MRS) Spring Meeting, Apr 2017, Phoenix, AZ, United States
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https://hal-mines-paristech.archives-ouvertes.fr/hal-01578984
Contributeur : Brigitte Hanot <>
Soumis le : mercredi 30 août 2017 - 11:04:17
Dernière modification le : mardi 27 mars 2018 - 16:06:22

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  • HAL Id : hal-01578984, version 1

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Gediminas Markevicius, Julien Jaxel, Tatiana Budtova, Arnaud Rigacci. Ambient-Dried Superinsulating and Monolithic Silica-Based Aerogels via the Use of Short Cellulose Fibers. Materials Research Society (MRS) Spring Meeting, Apr 2017, Phoenix, AZ, United States. 〈hal-01578984〉

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