Planar and uniplanar orientation in nanocellulose films: interpretation of 2D diffraction patterns step-by-step

Xiao Han, Pan Chen, Lengwan Li, Yoshiharu Nishiyama*, Xuan Yang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

X-ray diffraction (XRD) is widely used in cellulose structural characterization. The commonly used “powder” XRD assumes the sample is macroscopically isotropic. For cellulose fibrous samples, however, due to the high aspect ratio of the components, the structure is often anisotropic, and the texture affects the materials properties to a large extent. A simple setup of a point-focused X-ray beam and a two-dimensional detection of scattered X-ray is a practical tool to analyze the texture. We studied three types of cellulose nanofibril (CNF) films obtained by casting. 2,2,6,6-tetramethylpiper- idine-1-oxyl radical (TEMPO) oxidized one shows a high degree of (1–10) uniplanar orientation, whereas holocellulose CNF and enzyme-pretreated CNF showed planar orientation. In the planar orientation, the c-axis is preferentially oriented in the plane parallel to the film while within each fibril other crystallographic axis would be randomly distributed around the c-axis. Also, a clear peak can be detected at low angle corresponding to a d-spacing of 3–4 nm indicating a strong correlation perpendicular to the film at this length scale. This distance was the lowest for TEMPO-CNF and corroborates with the model of uniplanar orientation of rectangular cross-section. The numerically simulated azimuthal intensity distribution of hk0 reflections in the two types of texture agreed well with the experimental intensity distribution.

Original languageEnglish
Pages (from-to)8151-8159
Number of pages9
JournalCellulose
Volume30
Issue number13
DOIs
Publication statusPublished - Sept 2023

Keywords

  • X-ray diffraction
  • nanocellulose
  • planar orientation
  • uniplanar orientation

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Han, X., Chen, P., Li, L., Nishiyama, Y., & Yang, X. (2023). Planar and uniplanar orientation in nanocellulose films: interpretation of 2D diffraction patterns step-by-step. Cellulose, 30(13), 8151-8159. https://doi.org/10.1007/s10570-023-05411-5