Abstract
We report the anisotropic thermal expansion of a transparent nanopaper structure comprising cellulose nanofibers (CNFs). The coefficient of thermal expansion (CTE) of the nanopaper in the out-of-plane direction was 44.6 ppm/°C in the temperature range of 25–100°C, which is approximately five times larger than its CTE in the in-plane direction in the same temperature range (8.3 ppm/°C). Such a strong anisotropy in thermal expansion is mainly attributable to the anisotropic CTE values of single CNFs in the fiber axis and cross-sectional directions. We observed anisotropic thermal expansion even in a bioplastic composite containing only 2.5% w/w CNFs.
Highlights
Cellulose nanofibers (CNFs) are high-performance biobased materials with high mechanical strength and low thermal expansion
The cellulose acetate (CA)/cellulose nanofibers (CNFs) composite was prepared from a mixture of the CA solution (25 mL) and a 0.1% w/w TEMPO-oxidized CNF/DMAc dispersion (12 mL), according to the method described in a previous report (Soeta et al, 2017)
The TEMPO-oxidized CNFs are spontaneously arranged into a polydomain nematic order on the condensation process, such that a plywood-like nanostructure of the densified nematic-CNF arrangement is formed in the dried nanopapers. [See a reference by Zhao et al (2018) for details of the nematic ordering.] The nanopapers were ∼30-μm thick, and were optically transparent
Summary
Cellulose nanofibers (CNFs) are high-performance biobased materials with high mechanical strength and low thermal expansion. They are produced as water dispersions and can be formed into films. The production of CNF dispersions and films is well-established, and their uses are being explored. CNF films are often called “nanocellulose paper” or “nanopaper” (Henriksson et al, 2008; Zhao et al, 2018), because they are made from nanometer-wide fibers and form paper-like network structure at the nanoscale. Some transparent grades of the nanopapers are even called “transparent paper” (Nogi et al, 2009). The nanopaper structure can exploit the potential of CNFs, and combine mechanically and thermally superior properties
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
