PSI - Issue 52

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 52 (2024) 195–202

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© 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 Professor Ferri Aliabadi Abstract Although epoxy resin is widely used as a structural material such as transportation vehicles, replacing these materials with bio-based materials or its composites would greatly contribute to achieving a carbon-neutral society. Lignin produced from wood has been attracting attention as one of the naturally derived materials. Toward the application of lignin in composite materials, molecular dynamics simulations are performed on the mechanical characteristics of lignin/epoxy polymers, which are expected to be important candidates for the matrix of biobased composites. This study prepares two types of lignin/epoxy polymers with and without polyethylene glycol (PEG) sidechains, and effects of these side chains on the material characteristics are investigated through uniaxial tensile test and analysis of interfacial stability between lignin/epoxy polymer and functionalized graphene. Our calculation results show that PEG side chains improve Young’s modulus, strength and toughness, which may be induced by increasing the number of entanglement points between side chains. Further, the PEG side chains also improve the interfacial stability by forming hydrogen bonds between PEG and charge-biased functional groups on graphene sheet. We investigate molecular-scale mechanisms of interface stability difference between these models through analysis with radial distribution functions. In addition, by using an MD simulation algorithm that takes into account bond dissociation within the polymer chain, the stress-strain relationship of thermosetting polymers in the crosslinked state can be predicted. Fracture, Damage and Structural Health Monitoring Molecular Dynamics Simulation Considering Covalent Bond Dissociation for Lignin-based Composite Materials Mayu Morita a *, Yutaka Oya b , Nobuhiko Kato c , Kazuki Mori d , Jun Koyanagi e a Department of Materials Science and Technology, Graduate School of Tokyo Univeristy of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125 8585, Japan Department of Materials Science and Technology, Tokyo Univeristy of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan Abstract Although epoxy resin is widely used as a structural material such as transportation vehicles, replacing these materials with bio-based materials or its composites would greatly contribute to achieving a carbon-neutral society. Lignin produced from wood has been attracting attention as one of the naturally derived materials. Toward the application of lignin in composite materials, molecular dynamics simulations are performed on the mechanical characteristics of lignin/epoxy polymers, which are expected to be important candidates for the matrix of biobased composites. This study prepares two types of lignin/epoxy polymers with and without polyethylene glycol (PEG) sidechains, and effects of these side chains on the material characteristics are investigated through uniaxial tensile test and analysis of interfacial stability between lignin/epoxy polymer and functionalized graphene. Our calculation results show that PEG side chains improve Young’s modulus, strength and toughness, which may be induced by increasing the number of entanglement points between side chains. Further, the PEG side chains also improve the interfacial stability by forming hydrogen bonds between PEG and charge-biased functional groups on graphene sheet. We investigate molecular-scale mechanisms of interface stability difference between these models through analysis with radial distribution functions. In addition, by using an MD simulation algorithm that takes into account bond dissociation within the polymer chain, the stress-strain relationship of thermosetting polymers in the crosslinked state can be predicted. Keywords: Molecular dynamics simulation, composite materials, lignin, epoxy Fracture, Damage and Structural Health Monitoring Molecular Dynamics Simulation Considering Covalent Bond Dissociation for Lignin-based Composite Materials Mayu Morita a *, Yutaka Oya b , Nobuhiko Kato c , Kazuki Mori d , Jun Koyanagi e a Department of Materials Science and Technology, Graduate School of Tokyo Univeristy of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125 8585, Japan Department of Materials Science and Technology, Tokyo Univeristy of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan

Keywords: Molecular dynamics simulation, composite materials, lignin, epoxy *Corresponding author. Tel.: +81-80-5795-2643; fax: +81-35876-1411. E-mail address : 8218081@ed.alumni.tus.ac.jp *Corresponding author. Tel.: +81-80-5795-2643; fax: +81-35876-1411. E-mail address : 8218081@ed.alumni.tus.ac.jp

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 Professor Ferri Aliabadi 10.1016/j.prostr.2023.12.020 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 Professor Ferri Aliabadi 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 Professor Ferri Aliabadi