Elucidation of Relaxation Mechanism of Cellulose Nanofibers by Rheology and Fluorescence Microscopy

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K15348
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 35020:Polymer materials-related
• Research Institution: Forest Research and Management Organization
• Principal Investigator: Tanaka Reina 国立研究開発法人森林研究・整備機構, 森林総合研究所, 主任研究員 等 (00813510)
• Project Period (FY): 2021-02-01 – 2024-03-31
• Keywords: セルロースナノファイバー / 粘弾性 / 緩和 / 複屈折

Outline of Final Research Achievements

We measured the dynamic viscoelasticity and birefringence of individualized cellulose nanofibers (iCNFs) in the dilute region and compared them with the existing theory for viscoelasticity of semiflexible polymers (Morse theory) in order to clarify their relaxation behavior. The birefringence relaxation of iCNFs exhibited the orientation and bending modes similar to the other semiflexible polymers. On the other hand, the viscoelasticity of iCNFs could not be explained by the Morse theory at high frequencies, and the details of the viscoelastic relaxation could not be clarified. This result was independent of raw materials and preparation conditions of iCNFs. Therefore, iCNFs are considered to be a non-ideal semiflexible polymer that cannot be explained by the existing Morse theory. Furthermore, a similar study in the semi-dilute region showed that the orientation (rotational) relaxation mode of iCNFs had a stronger concentration dependence than that of the other semiflexible polymers.

Free Research Field

ナノセルロース分散系のレオロジー

Academic Significance and Societal Importance of the Research Achievements

CNFの緩和は、そのサイズやサイズ分布、屈曲性を反映する基礎的な指標である。さらに、CNF製品の成型加工プロセスの最適化に必要な指標である。従って、CNFの工業利用を促進するためには、本研究が必須である。本研究成果ではCNFの詳細な粘弾性緩和は解明できなかったものの、今後に解明するための道筋を明らかにできた。特に、分散媒の粘弾性への影響は解明できていないため、今後引き続きこの検討を行う。