Molecular origin of asymmetric yield surface of crosslinked epoxy polymers

In this study, we investigate the multiaxial mechanical behavior of thermosetting epoxy polymers and explore the asymmetry between tension and compression in their yield surfaces at the molecular level using molecular dynamics simulations, complemented by experimental validation through polymer synt...

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Main Authors: Jinyoung Kim, Kyeongmin Hong, Yong-Seok Choi, Dayoung Jang, Jang-Woo Han, Hyungbum Park
Format: Article
Language:English
Published: Elsevier 2025-02-01
Series:Polymer Testing
Online Access:http://www.sciencedirect.com/science/article/pii/S0142941825000248
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author Jinyoung Kim
Kyeongmin Hong
Yong-Seok Choi
Dayoung Jang
Jang-Woo Han
Hyungbum Park
author_facet Jinyoung Kim
Kyeongmin Hong
Yong-Seok Choi
Dayoung Jang
Jang-Woo Han
Hyungbum Park
author_sort Jinyoung Kim
collection DOAJ
description In this study, we investigate the multiaxial mechanical behavior of thermosetting epoxy polymers and explore the asymmetry between tension and compression in their yield surfaces at the molecular level using molecular dynamics simulations, complemented by experimental validation through polymer synthesis. After constructing an atomistic-scale amorphous epoxy system based on molecular dynamics simulations, we derived equivalent stress–strain curves and yield surfaces as functions of the degree of crosslinking through biaxial deformation analysis. The results show that increasing the degree of crosslinking leads to an increase in equivalent stress in all loading directions, resulting in an expansion of the yield surface. Notably, a more accelerated expansion of the yield surface in the biaxial compression direction was observed at higher degrees of crosslinking, which is attributed to a deformation mechanism that more effectively accommodates stress in this loading direction. This unique deformation behavior is attributed to high non-bonded stress arising from reduced polymer chain mobility by crosslinking effect. To experimentally validate the deformation mechanisms, epoxy polymer samples were synthesized, and uniaxial tensile and plane-strain compression (PSC) tests were conducted to obtain stress–strain profiles and yield surfaces according to different degrees of cure. These results provide fundamental insights into the distinct mechanical properties of polymer materials, such as the asymmetry of the yield surface, by revealing their behavior at the molecular level.
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institution Kabale University
issn 1873-2348
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publishDate 2025-02-01
publisher Elsevier
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series Polymer Testing
spelling doaj-art-0b3bbbde7f5e478aa15455d26d56dca62025-02-02T05:26:37ZengElsevierPolymer Testing1873-23482025-02-01143108710Molecular origin of asymmetric yield surface of crosslinked epoxy polymersJinyoung Kim0Kyeongmin Hong1Yong-Seok Choi2Dayoung Jang3Jang-Woo Han4Hyungbum Park5Department of Mechanical Engineering, Incheon National University, (Songdo-dong) 119 Academy-ro, Yeonsu-gu, Incheon, 22012, Republic of KoreaInstitute of Advanced Composite Materials, Korea Institute of Science and Technology (KIST), 92 Chudong-ro, Bongdong-eup, Wanju-gun, Jeollabuk-do, 55324, Republic of KoreaInstitute of Advanced Composite Materials, Korea Institute of Science and Technology (KIST), 92 Chudong-ro, Bongdong-eup, Wanju-gun, Jeollabuk-do, 55324, Republic of KoreaDepartment of Mechanical Design Engineering, Kumoh National Institute of Technology, 61, Daehak-ro, Gumi-si, Gyeongsangbuk-do, 39177, Republic of KoreaDepartment of Mechanical Design Engineering, Kumoh National Institute of Technology, 61, Daehak-ro, Gumi-si, Gyeongsangbuk-do, 39177, Republic of KoreaDepartment of Mechanical Engineering, Incheon National University, (Songdo-dong) 119 Academy-ro, Yeonsu-gu, Incheon, 22012, Republic of Korea; Corresponding author.In this study, we investigate the multiaxial mechanical behavior of thermosetting epoxy polymers and explore the asymmetry between tension and compression in their yield surfaces at the molecular level using molecular dynamics simulations, complemented by experimental validation through polymer synthesis. After constructing an atomistic-scale amorphous epoxy system based on molecular dynamics simulations, we derived equivalent stress–strain curves and yield surfaces as functions of the degree of crosslinking through biaxial deformation analysis. The results show that increasing the degree of crosslinking leads to an increase in equivalent stress in all loading directions, resulting in an expansion of the yield surface. Notably, a more accelerated expansion of the yield surface in the biaxial compression direction was observed at higher degrees of crosslinking, which is attributed to a deformation mechanism that more effectively accommodates stress in this loading direction. This unique deformation behavior is attributed to high non-bonded stress arising from reduced polymer chain mobility by crosslinking effect. To experimentally validate the deformation mechanisms, epoxy polymer samples were synthesized, and uniaxial tensile and plane-strain compression (PSC) tests were conducted to obtain stress–strain profiles and yield surfaces according to different degrees of cure. These results provide fundamental insights into the distinct mechanical properties of polymer materials, such as the asymmetry of the yield surface, by revealing their behavior at the molecular level.http://www.sciencedirect.com/science/article/pii/S0142941825000248
spellingShingle Jinyoung Kim
Kyeongmin Hong
Yong-Seok Choi
Dayoung Jang
Jang-Woo Han
Hyungbum Park
Molecular origin of asymmetric yield surface of crosslinked epoxy polymers
Polymer Testing
title Molecular origin of asymmetric yield surface of crosslinked epoxy polymers
title_full Molecular origin of asymmetric yield surface of crosslinked epoxy polymers
title_fullStr Molecular origin of asymmetric yield surface of crosslinked epoxy polymers
title_full_unstemmed Molecular origin of asymmetric yield surface of crosslinked epoxy polymers
title_short Molecular origin of asymmetric yield surface of crosslinked epoxy polymers
title_sort molecular origin of asymmetric yield surface of crosslinked epoxy polymers
url http://www.sciencedirect.com/science/article/pii/S0142941825000248
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AT dayoungjang molecularoriginofasymmetricyieldsurfaceofcrosslinkedepoxypolymers
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AT hyungbumpark molecularoriginofasymmetricyieldsurfaceofcrosslinkedepoxypolymers