PSI - Issue 45

ScienceDirect Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2022) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2022) 000 – 000 Available online at www.sciencedirect.com Procedia Structural Integrity 45 (2023) 125–131

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2452-3216 © 2023 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of Prof. Andrei Kotousov 10.1016/j.prostr.2023.05.005 2452-3216 © 2023 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of Prof. Andrei Kotousov 2452-3216 © 2023 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of Prof. Andrei Kotousov * Corresponding author. Tel.: +81-3-5284-5475, fax: +81-3-5284-5693 E-mail address: 20udm03@ms.dendai.ac.jp 1. Introduction The linear relationship between the adhesion strength F and surface free energy γs of adherends in adhesion between epoxy resin and polymer was reported by Levine et al. (1964). However, no data were previously reported in the The linear relationship between the adhesion strength F and surface free energy γs of adherends in adhesion between epoxy resin and polymer was reported by Levine et al. (1964). However, no data were previously reported in the © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of Prof. Andrei Kotousov Abstract The deviation from the linear relationship between the adhesion strength and surface free energy on a low energy surface was observed for the first time. Although the linear relationship between the adhesion strength and surface free energy in the adhesion between epoxy resin and polymer was previously reported, it was only observed for the region of surface free energy greater than 20 mN/m. In particular, no data were previously reported for the region of surface free energy less than 20 mN/m. The aim of this study was to investigate the existence of the linear relationship in the region of surface free energy less than 20 mN/m. The linear relationship was investigated for the case wherein the epoxy resin adhesive was diluted. No data were previously reported due to the difficulty associated with the preparation of the low surface free energy adherend. In this study, the low surface free energy adherend was prepared by coating the adherend with a low surface energy layer such as a polytetrafluoroethylene particle dispersion composite. The lower limit of the linear relationship between the adhesion strength and surface free energy extended from the conventional value of 20 mN/m to 15.3 mN/m. In the region of surface free energy less than 15.3 mN/m to 2.3 mN/m, the adhesion strength was almost constant, which represents a deviation from the linear relationship. The abovementioned phenomena were observed when the epoxy resin was diluted by egg white by up to 40 vol.%. Abstract The deviation from the linear relationship between the adhesion strength and surface free energy on a low energy surface was observed for the first time. Although the linear relationship between the adhesion strength and surface free energy in the adhesion between epoxy resin and polymer was previously reported, it was only observed for the region of surface free energy greater than 20 mN/m. In particular, no data were previously reported for the region of surface free energy less than 20 mN/m. The aim of this study was to investigate the existence of the linear relationship in the region of surface free energy less than 20 mN/m. The linear relationship was investigated for the case wherein the epoxy resin adhesive was diluted. No data were previously reported due to the difficulty associated with the preparation of the low surface free energy adherend. In this study, the low surface free energy adherend was prepared by coating the adherend with a low surface energy layer such as a polytetrafluoroethylene particle dispersion composite. The lower limit of the linear relationship between the adhesion strength and surface free energy extended from the conventional value of 20 mN/m to 15.3 mN/m. In the region of surface free energy less than 15.3 mN/m to 2.3 mN/m, the adhesion strength was almost constant, which represents a deviation from the linear relationship. The abovementioned phenomena were observed when the epoxy resin was diluted by egg white by up to 40 vol.%. Keywords: adhesion; low surface free energy; polymer; adhesive; adherend; epoxy resin 17th Asia-Pacific Conference on Fracture and Strength and the 13th Conference on Structural Integrity and Failure (APCFS 2022 & SIF 2022) Deviation from linear relationship between adhesion strength and 17th Asia-Pacific Conference on Fracture and Strength and the 13th Conference on Structural Integrity and Failure (APCFS 2022 & SIF 2022) Deviation from linear relationship between adhesion strength and surface free energy on a low energy surface Kentaro Yamauchi a, *, Yuki Shiotani a , Hiroyuki Saito a a Graduate School of Tokyo Denki University, 5 Senju-Asahi-cho, Adachi-ku, Tokyo 120-8551, Japan surface free energy on a low energy surface Kentaro Yamauchi a, *, Yuki Shiotani a , Hiroyuki Saito a a Graduate School of Tokyo Denki University, 5 Senju-Asahi-cho, Adachi-ku, Tokyo 120-8551, Japan Keywords: adhesion; low surface free energy; polymer; adhesive; adherend; epoxy resin * Corresponding author. Tel.: +81-3-5284-5475, fax: +81-3-5284-5693 E-mail address: 20udm03@ms.dendai.ac.jp 1. Introduction