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Title: Merging flexibility with superinsulation : machinable, nanofibrous pullulan-silica aerogel composites
Authors : Zhao, Shanyu
Emery, Olivier
Wohlhauser, Anja
Koebel, Matthias M.
Adlhart, Christian
Malfait, Wim J.
Published in : Materials and design
Volume(Issue) : 160
Pages : 294
Pages to: 302
Publisher / Ed. Institution : Elsevier
Issue Date: 2018
License (according to publishing contract) : Licence according to publishing contract
Type of review: Peer review (Publication)
Language : English
Subjects : Nanocomposite; Polysaccharide; Nanofibers; Hybrid aerogels; Densification
Subject (DDC) : 540: Chemistry
620: Engineering
Abstract: Freeze-dried nanofibrous scaffolds are flexible, but typically have high thermal conductivities. Conversely, silica aerogel has an ultra-low thermal conductivity, but is brittle. Here, the impregnation of pullulan/PVA nanofiber scaffolds with hydrophobic silica aerogel decreased the thermal conductivity from 31.4 to 17.7 mW/(m·K). The compatibility between the silylated nanofibers and the silica aerogel promotes the overgrowth of silica particles onto the fiber surfaces and the fiber incorporation. The composites display improved compressive and tensile properties compared to the neat pullulan scaffold and silica aerogel. The composite's E-modulus is 234 kPa compared to 4 kPa for the pullulan scaffold and 102 kPa for the silica aerogel. The composite's tensile strength is five times higher than that of the silica aerogel. Because of its reduced brittleness, the pullulan-silica aerogel composites can be shaped using a sharp blade. The composites can sustain uniaxial compression up to 80% strain, but the decompressed composites display two times higher densities because the strain is partially irreversible. This densification reduces thermal conductivity to 16.3 mW/(m·K) and increases final compressive strength by a factor of seven. Both the as prepared and densified composites demonstrate unique material properties in terms of thermal conductivity, mechanical strength and machinability.
Departement: Life Sciences and Facility Management
Organisational Unit: Institute of Chemistry and Biotechnology (ICBT)
Publication type: Article in scientific Journal
DOI : 10.1016/j.matdes.2018.09.010
ISSN: 0264-1275
Restricted until : 2020-12-15
Appears in Collections:Publikationen Life Sciences und Facility Management

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