Measurement of flow-induced orientation of nanofiber suspension in the molding flow by polarization imaging

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K15299
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 26030:Composite materials and interfaces-related
• Research Institution: Niigata University
• Principal Investigator: Sato Taisuke 新潟大学, 研究推進機構, 助教 (70778703)
• Project Period (FY): 2019-04-01 – 2021-03-31
• Keywords: セルロースナノファイバー / 繊維分散流体 / サスペンション / 偏光イメージング / 繊維配向 / 流動複屈折 / 平面流れ

Outline of Final Research Achievements

The aim of this research is to clarify the fiber orientation in the molding flow of the cellulose nanofiber suspension. In this study, rheology properties and distribution of the flow-induced birefringence were measured. In addition, polarization imaging device, which was configured by low price optical elements, was developed to measure the fiber orientation. The test fluid exhibits viscosity with shear-thinning behavior and strong elasticity. In the contraction flow, fibers were aligned strongly in the flow direction. In the downstream region, the birefringence decreases and reaches a constant value. The result shows that the fiber orientation induced by the contraction flow was varied to the orientation in the shear flow. Furthermore, it was found that the distance at which the birefringence reaches a constant value is not affected by the flow rate, contraction ratio and aspect ratio.

Free Research Field

流体工学

Academic Significance and Societal Importance of the Research Achievements

現在セルロースナノファイバー（CNF）は，複合材料の強化材としての応用が考えられている。繊維複合材料の成形において，製品中の繊維配向は，成形加工中の材料の流動でほぼ決定され，それが複合材料の歪やソリ，強度ムラといった欠陥に大きく影響する。したがって，目的とする良い材料特性を発現させるには，CNFを含んだ流体の流動に関する基礎的な知見を得ることが極めて重要である。本研究ではCNF分散系において，繊維配向を定量的に評価しており，この成果は，CNFを用いた複合材料の品質向上に大きく寄与すると期待される。