Variety of the memory retention ability in the memory effect of paste

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K03886
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 13040:Biophysics, chemical physics and soft matter physics-related
• Research Institution: Nihon University
• Principal Investigator: NAKAHARA Akio 日本大学, 理工学部, 教授 (60297778)
• Co-Investigator(Kenkyū-buntansha): 狐崎 創 奈良女子大学, 自然科学系, 教授 (00301284)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 記憶効果 / レオロジー / 破壊の制御 / 塑性流体 / コロイド

Outline of Final Research Achievements

Paste remembers the direction of its vibration or flow due to its plasticity, then the memory determines the preferential direction for cracks to propagate, thus the memory of paste can be visualized as a morphology of desiccation crack pattern. In our research, we presented an image analysis method to characterize the type and the strength of the memory of paste by analyzing the anisotropic crack pattern using information entropy. Then, we perform experiment in which we add polysaccharide to a paste. By changing the amount of polysaccharide which add to a paste, we can control the situation whether the dominant interparticle interaction is attractive or repulsive, and thus succeeded in assisting or eliminating memory effect of paste. Finally, we performed experiments using a rheometer, and found that only oscillatory shear strain with a small amplitude is necessary for memory of vibration; large shear deformation is sufficient for memory of flow.

Free Research Field

ソフトマター

Academic Significance and Societal Importance of the Research Achievements

破壊や地震は身近な現象でありながら、いつどこがどのように壊れるかが状況に応じて逐次変化していくので、防災上の正確な予測や対策が立てにくい。本研究では、塑性を持つペーストが揺れや流れなどの己の動きを記憶してその後の壊れやすい方向が決まるという現象を研究することで、サイエンスとしてはソフトマターのレオロジーの面白さの基礎研究だけでなく、破壊の制御や破壊の前駆現象の予知、さらには過去に起こった破壊現象の原因究明へと応用できるので、人類にとって重要なテーマである。今回、揺れの記憶と流れの記憶の転移条件が分かったことで、どの程度の変形でどの方向に物質が破れやすくなるかが予測できるようになり意義がある。