title: Crystallite Size Effect on Thermal Conductive Properties of Nonwoven Nanocellulose Sheets.
abstract: The thermal conductive properties, including the thermal diffusivity and resultant thermal conductivity, of nonwoven nanocellulose sheets were investigated by separately measuring the thermal diffusivity of the sheets in the in-plane and thickness directions with a periodic heating method. The cross-sectional area (or width) of the cellulose crystallites was the main determinant of the thermal conductive properties. Thus, the results strongly indicate that there is a crystallite size effect on phonon conduction within the nanocellulose sheets. The results also indicated that there is a large interfacial thermal resistance between the nanocellulose surfaces. The phonon propagation velocity (i.e., the sound velocity) within the nanocellulose sheets was estimated to be ∼800 m/s based on the relationship between the thermal diffusivities and crystallite widths. The resulting in-plane thermal conductivity of the tunicate nanocellulose sheet was calculated to be ∼2.5 W/mK, markedly higher than other plastic films available for flexible electronic devices.
authors.affiliation: College of Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501, Japan.
authors.forename: Kojiro
authors.initials: K
authors.lastname: Uetani
authors.affiliation: College of Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501, Japan.
authors.forename: Takumi
authors.initials: T
authors.lastname: Okada
authors.affiliation: College of Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501, Japan.
authors.forename: Hideko T
authors.initials: HT
authors.lastname: Oyama
mesh_terms: D002482:Cellulose / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry; D013814:Thermal Conductivity
chemical_list: D002482:Cellulose