Cellulose fibre – silica aerogel thermal superinsulation composites

Abstract : Thermal superinsulation materials (typically aerogels, with thermal conductivity below that of air: 0.025 W/m.K at room conditions) are usually fabricated from mesoporous alcogels with the use of supercritical (sc) CO2 for drying. By use of supercritical fluid, the mesoporous structure of the wet matrix, is preserved as the pore liquid is removed. This process is, however, cost prohibitive and involves specific process parameters (e.g. high pressure) which make it difficult to up-scale. Ambient pressure drying therefore is much preferred. The challenge is preserving monolithic shape of the sample which is stressed due to the high surface tension of pore liquid during evaporative drying. We propose that this could be addressed by incorporation of short cellulose fibers into silica alcogels allowing making monolithic, not brittle and thermally superinsulating aerogels via ambient pressure drying instead of sc drying. We used Tencel as model fibers. The aerogels with 0.5 to 3 final vol% of fibers were synthesized and hydrophobized before drying. Fiber presence allowed fabrication of monolithic aerogels via ambient drying. The effects of different cellulosic fibers on the properties of silica-based composite aerogels produced both via ambient drying and the sc CO2 drying methods are compared. Thermal conductivity of composites was typically below 0.018 W/m.K for composites containing <2 vol% fiber fraction and increased slightly with increasing fiber concentration. The bulk densities of ambient and sc CO2 dried aerogels were similar (typically in the 0.1 – 0.125 g/cm3 range). The addition of cellulose fibers significantly increased the Young’s modulus of both the sc dried aerogels and ambient-dried aerogels. This original aerogel preparation method was also successfully demonstrated with natural fibers from wood with different lignin content and flax. Future perspective in polysaccharide research: This application may be particularly interesting for the pulp and recycled fibre industries because they produce short fibers (elementary fibres with <10 mm length). Additionally similar composite approach could be potentially applied for polysaccharide based aerogels as well for their reinforcement.
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https://hal-mines-paristech.archives-ouvertes.fr/hal-01436060
Contributeur : Magalie Prudon <>
Soumis le : lundi 16 janvier 2017 - 10:39:04
Dernière modification le : lundi 12 novembre 2018 - 11:02:15

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  • HAL Id : hal-01436060, version 1

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Gediminas Markevicius, Julien Jaxel, Tatiana Budtova, Arnaud Rigacci. Cellulose fibre – silica aerogel thermal superinsulation composites. 2nd International EPNOE Junior Scientists Meeting - Future Perspectives in Polysaccharides Research, Oct 2016, Sophia Antipolis, France. ⟨hal-01436060⟩

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