Anisotropic, lightweight, strong, and super thermally insulating nanowood with naturally aligned nanocelluloseShow others and affiliations
2018 (English)In: Science Advances, ISSN 0036-8156, E-ISSN 2375-2548, Vol. 4, no 3, article id eaar3724Article in journal (Refereed) Published
Abstract [en]
There has been a growing interest in thermal management materials due to the prevailing energy challenges and unfulfilled needs for thermal insulation applications. We demonstrate the exceptional thermal management capabilities of a large-scale, hierarchal alignment of cellulose nanofibrils directly fabricated fromwood, hereafter referred to as nanowood. Nanowood exhibits anisotropic thermal properties with an extremely low thermal conductivity of 0.03W/m·K in the transverse direction (perpendicular to the nanofibrils) and approximately two times higher thermal conductivity of 0.06W/m·K in the axial direction due to the hierarchically aligned nanofibrilswithin the highly porous backbone. The anisotropy of the thermal conductivity enables efficient thermal dissipation along the axial direction, thereby preventing local overheating on the illuminated side while yielding improved thermal insulation along the backside that cannot be obtained with isotropic thermal insulators. The nanowood also shows a low emissivity of <5% over the solar spectrum with the ability to effectively reflect solar thermal energy. Moreover, the nanowood is lightweight yet strong, owing to the effective bonding between the aligned cellulose nanofibrils with a high compressive strength of 13 MPa in the axial direction and 20MPa in the transverse direction at 75% strain, which exceeds other thermal insulation materials, such as silica and polymer aerogels, Styrofoam, and wool. The excellent thermal management, abundance, biodegradability, high mechanical strength, low mass density, and manufacturing scalability of the nanowood make this material highly attractive for practical thermal insulation applications.
Place, publisher, year, edition, pages
American Association for the Advancement of Science , 2018. Vol. 4, no 3, article id eaar3724
Keywords [en]
Anisotropy, Biodegradability, Cellulose, Compressive strength, Insulation, Nanofibers, Silica, Solar energy, Strength of materials, Temperature control, Thermal conductivity, Thermal insulating materials, Thermal variables control, Cellulose nanofibrils, High mechanical strength, Insulation applications, Low thermal conductivity, Management capabilities, Solar thermal energy, Thermal insulation materials, Thermal management material, Thermal insulation
National Category
Chemical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-227394DOI: 10.1126/sciadv.aar3724ISI: 000427892700039Scopus ID: 2-s2.0-85044145510OAI: oai:DiVA.org:kth-227394DiVA, id: diva2:1211079
Note
Export Date: 9 May 2018; Article; Correspondence Address: Hu, L.; Department of Materials Science and Engineering, University of MarylandUnited States; email: binghu@umd.edu. QC 20180530
2018-05-302018-05-302018-10-19Bibliographically approved