Skip to main content

ORIGINAL RESEARCH article

Front. Mech. Eng.
Sec. Tribology
Volume 10 - 2024 | doi: 10.3389/fmech.2024.1422412
This article is part of the Research Topic Visualization Techniques in Tribology View all 5 articles

In-Situ Vibrational Spectroscopic Observation for Thermally activated Structural Changes of 100% Cellulose Nanofiber Molding with Ultralow Friction

Provisionally accepted
Hikaru Okubo Hikaru Okubo 1*Tomori Ishikawa Tomori Ishikawa 1Hiromi Hashiba Hiromi Hashiba 2Toru Inamochi Toru Inamochi 2Ken Nakano Ken Nakano 1
  • 1 Yokohama National University, Yokohama, Japan
  • 2 Chuetsu Pulp & Paper Co., Ltd., Takaoka, Japan

The final, formatted version of the article will be published soon.

    This paper reports the thermally activated ultralow friction of 100% cellulose nanofiber (CNF) molding. The mechanism of friction reduction was investigated using a laboratory-built in-situ Raman tribometer. Our experimental results showed that a CNF molding exhibited an ultralow friction coefficient of below 0.04 in a CNF ring and steel disk tribopair under high-temperature conditions (T >100 °C). The results of the temperature-rise friction test showed that the friction coefficient of the CNF molding strongly depended on the temperature and decreased linearly with increasing temperature. The in situ tribo-Raman monitoring results, during friction, indicated a change in the structure of the CNF molding. Therefore, the crystallinity indices and lengths of the CNF fibers gradually changed as the temperature increased. Moreover, transfer tribofilms were observed on the counter-steel surface against the CNF rings. When the CNF molding exhibited thermally activated ultralow friction, the tribofilm was mainly composed of cellulose and graphitic carbon. Our results suggest that the thermal and friction-activated structural transformations of CNF molding and CNF-derived transfer film formation are pivotal factors contributing to the ultralow friction phenomenon observed in CNF molding at high temperatures.

    Keywords: cellulose nanofibers, CNF, Ultralow friction, Raman, In-situ, Transfer film

    Received: 24 Apr 2024; Accepted: 14 Jun 2024.

    Copyright: © 2024 Okubo, Ishikawa, Hashiba, Inamochi and Nakano. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Hikaru Okubo, Yokohama National University, Yokohama, Japan

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.