1
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Yamamoto S, Tsuji Y, Kuwahara R, Yoshizawa K, Tanaka K. Effect of Condensed Water at an Alumina/Epoxy Resin Interface on Curing Reaction. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:12613-12621. [PMID: 38767655 PMCID: PMC11191686 DOI: 10.1021/acs.langmuir.4c01081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2024] [Revised: 05/07/2024] [Accepted: 05/09/2024] [Indexed: 05/22/2024]
Abstract
The adhesion of epoxy adhesives to aluminum materials is an important issue in assembling parts for lightweight mobility. Aluminum surfaces typically possess an oxide layer, which readily adsorbs water. In this study, the aggregation states of water and its effect on the curing reaction were examined by placing a water layer between an amorphous alumina surface and a mixture of epoxy and amine components. This study used molecular dynamics simulations and density functional theory calculations. Before the reaction, water molecules strongly adsorbed onto the alumina surface, aggregating excess water. Some water diffused into the epoxy/amine mixture, accelerating the diffusion of unreacted substances. This led to faster reaction kinetics, particularly in proximity to the alumina surface. The adsorption of water molecules onto the alumina surface and the aggregation of excess water were similarly observed even after the curing process. Subsequently, the interaction between the alumina surface and various functional groups of the epoxy/amine mixture was evaluated before and after the reaction. Epoxy monomers had little interaction with the alumina surface before the reaction, whereas hydroxy groups formed by the ring-opening reaction of epoxy groups exhibited notable interaction. Conversely, sulfonyl and amino groups in amine compounds formed hydrogen bonds with OH groups on the alumina surface before the reaction. However, after the reaction, amino groups weakened their interaction with the alumina OH groups as they transformed from primary to tertiary during the curing reaction. Both epoxy and amine monomers/fragments similarly interacted with water molecules, both before and after the reaction. The insights gained from this study are expected to contribute to a better understanding of the impact of moisture absorption on the application of epoxy resins.
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Affiliation(s)
- Satoru Yamamoto
- Center
for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan
| | - Yuta Tsuji
- Faculty
of Engineering Sciences, Kyushu University, Kasuga 816-8580, Japan
| | | | - Kazunari Yoshizawa
- Institute
for Materials Chemistry and Engineering, Kyushu University, Fukuoka 819-0395, Japan
| | - Keiji Tanaka
- Center
for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan
- Department
of Applied Chemistry, Kyushu University, Fukuoka 819-0395, Japan
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2
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Vogelwaid J, Bayer M, Walz M, Hampel F, Kutuzova L, Lorenz G, Kandelbauer A, Jacob T. Optimizing Epoxy Molding Compound Processing: A Multi-Sensor Approach to Enhance Material Characterization and Process Reliability. Polymers (Basel) 2024; 16:1540. [PMID: 38891486 PMCID: PMC11174805 DOI: 10.3390/polym16111540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Revised: 05/22/2024] [Accepted: 05/28/2024] [Indexed: 06/21/2024] Open
Abstract
The in-line control of curing during the molding process significantly improves product quality and ensures the reliability of packaging materials with the required thermo-mechanical and adhesion properties. The choice of the morphological and thermo-mechanical properties of the molded material, and the accuracy of their determination through carefully selected thermo-analytical methods, play a crucial role in the qualitative prediction of trends in packaging product properties as process parameters are varied. This work aimed to verify the quality of the models and their validation using a highly filled molding resin with an identical chemical composition but 10 wt% difference in silica particles (SPs). Morphological and mechanical material properties were determined by dielectric analysis (DEA), differential scanning calorimetry (DSC), warpage analysis and dynamic mechanical analysis (DMA). The effects of temperature and injection speed on the morphological properties were analyzed through the design of experiments (DoE) and illustrated by response surface plots. A comprehensive approach to monitor the evolution of ionic viscosity (IV), residual enthalpy (dHrest), glass transition temperature (Tg), and storage modulus (E) as a function of the transfer-mold process parameters and post-mold-cure (PMC) conditions of the material was established. The reliability of Tg estimation was tested using two methods: warpage analysis and DMA. The noticeable deterioration in the quality of the analytical signal for highly filled materials at high cure rates is discussed. Controlling the temperature by increasing the injection speed leads to the formation of a polymer network with a lower Tg and an increased storage modulus, indicating a lower density and a more heterogeneous structure due to the high heating rate and shear heating effect.
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Affiliation(s)
- Julian Vogelwaid
- Mobility Electronics, Engineering Technology Polymer & Packaging, Robert Bosch GmbH, 72770 Reutlingen, Germany; (M.B.); (M.W.); (F.H.)
- Fakultät für Naturwissenschaften, Institut für Elektrochemie, Universität Ulm, 89081 Ulm, Germany;
| | - Martin Bayer
- Mobility Electronics, Engineering Technology Polymer & Packaging, Robert Bosch GmbH, 72770 Reutlingen, Germany; (M.B.); (M.W.); (F.H.)
| | - Michael Walz
- Mobility Electronics, Engineering Technology Polymer & Packaging, Robert Bosch GmbH, 72770 Reutlingen, Germany; (M.B.); (M.W.); (F.H.)
| | - Felix Hampel
- Mobility Electronics, Engineering Technology Polymer & Packaging, Robert Bosch GmbH, 72770 Reutlingen, Germany; (M.B.); (M.W.); (F.H.)
- Fakultät für Life Sciences, Reutlingen University, 72762 Reutlingen, Germany; (L.K.); (G.L.); (A.K.)
| | - Larysa Kutuzova
- Fakultät für Life Sciences, Reutlingen University, 72762 Reutlingen, Germany; (L.K.); (G.L.); (A.K.)
| | - Günter Lorenz
- Fakultät für Life Sciences, Reutlingen University, 72762 Reutlingen, Germany; (L.K.); (G.L.); (A.K.)
| | - Andreas Kandelbauer
- Fakultät für Life Sciences, Reutlingen University, 72762 Reutlingen, Germany; (L.K.); (G.L.); (A.K.)
- Department of Material Sciences and Process Engineering, Institute of Wood Technology and Renewable Materials, University of Natural Resources and Life Sciences, 1180 Vienna, Austria
| | - Timo Jacob
- Fakultät für Naturwissenschaften, Institut für Elektrochemie, Universität Ulm, 89081 Ulm, Germany;
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3
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Saeki S, Kawaguchi D, Tsuji Y, Yamamoto S, Yoshizawa K, Tanaka K. Electronic Interaction of Epoxy Resin with Copper at the Adhered Interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:9725-9731. [PMID: 38652685 PMCID: PMC11080069 DOI: 10.1021/acs.langmuir.4c00711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 04/05/2024] [Accepted: 04/09/2024] [Indexed: 04/25/2024]
Abstract
A better understanding of the aggregation states of adhesive molecules in the interfacial region with an adherend is crucial for controlling the adhesion strength and is of great inherent academic interest. The adhesion mechanism has been described through four theories: adsorption, mechanical, diffusion, and electronic. While interfacial characterization techniques have been developed to validate the aforementioned theories, that related to the electronic theory has not yet been thoroughly studied. We here directly detected the electronic interaction between a commonly used thermosetting adhesive, cured epoxy of diglycidyl ether of bisphenol A (DGEBA) and 4,4'-diaminodiphenylmethane (DDM), and copper (Cu). This study used a combination of density functional theory (DFT) calculations and femtosecond transient absorption spectroscopic (TAS) measurements as this epoxy adhesive-Cu pairing is extensively used in electronic device packaging. The DFT calculations predicted that π electrons in a DDM molecule adsorbed onto the Cu surface flowed out onto the Cu surface, resulting in a positive charge on the DDM. TAS measurements for the Cu/epoxy multilayer film, a model sample containing many metal/adhesive interfaces, revealed that the electronic states of excited DDM moieties at the Cu interface were different from those in the bulk region. These results were in good accordance with the prediction by DFT calculations. Thus, it can be concluded that TAS is applicable to characterize the electronic interaction of adhesives with metal adherends in a nondestructive manner.
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Affiliation(s)
- Shintaro Saeki
- Department
of Applied Chemistry, Kyushu University, Fukuoka 819-0395, Japan
| | - Daisuke Kawaguchi
- Department
of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
| | - Yuta Tsuji
- Faculty
of Engineering Sciences, Kyushu University, Fukuoka 816-8580, Japan
| | - Satoru Yamamoto
- Center
for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan
| | - Kazunari Yoshizawa
- Institute
for Materials Chemistry and Engineering and IRCCS, Kyushu University, Nishi-ku, Fukuoka 819-0395, Japan
| | - Keiji Tanaka
- Department
of Applied Chemistry, Kyushu University, Fukuoka 819-0395, Japan
- Center
for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan
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4
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Analysis of the glass effect and Trommsdorff effect during bulk polymerization of methyl methacrylate, ethyl methacrylate, and butyl methacrylate. Polym J 2023. [DOI: 10.1038/s41428-022-00746-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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5
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Tominaga R, Takeda Y, Kotera M, Suzuki Y, Matsumoto A. Non-destructive observation of internal structures of epoxy monolith and co-continuous network polymer using X-ray CT imaging for elucidation of their unique mechanical features and fracture mechanism. POLYMER 2022. [DOI: 10.1016/j.polymer.2022.125433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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6
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Nguyen HK, Shundo A, Liang X, Yamamoto S, Tanaka K, Nakajima K. Unraveling Nanoscale Elastic and Adhesive Properties at the Nanoparticle/Epoxy Interface Using Bimodal Atomic Force Microscopy. ACS APPLIED MATERIALS & INTERFACES 2022; 14:42713-42722. [PMID: 36070235 DOI: 10.1021/acsami.2c12335] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The addition of a small fraction of solid nanoparticles to thermosetting polymers can substantially improve their fracture toughness, while maintaining various intrinsic thermomechanical properties. The underlying mechanism is largely related to the debonding process and subsequent formation of nanovoids at a nanoscale nanoparticle/epoxy interface, which is thought to be associated with a change in the structural and mechanical properties of the formed epoxy network at the interface compared with the matrix region. However, a direct characterization of the local physical properties at this nanoscale interface remains significantly challenging. Here, we employ a recently developed bimodal atomic force microscopy technique for the direct mapping of nanoscale elastic and adhesive responses of an amine-cured epoxy resin filled with ∼50 nm diameter silica nanoparticles. The obtained elastic modulus and dissipated energy maps with high spatial resolution evidence the existence of a ∼20-nm-thick interfacial epoxy layer surrounding the nanoparticles, which exhibits a reduced modulus and weaker adhesive response in comparison with the matrix properties. While the presence of such a soft and weak-adhesive interfacial layer is found not to affect the architecture of structural heterogeneities in the epoxy matrix, it conceivably supports the toughening mechanism related to the debonding and plastic nanovoid growth at the silica/epoxy interface. The incorporation of this soft interfacial layer into the Halpin-Tsai model also provides a good explanation for the effect of the silica fraction on the tensile modulus of cured epoxy nanocomposites.
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Affiliation(s)
- Hung K Nguyen
- Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo 152-8552, Japan
| | - Atsuomi Shundo
- Center for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan
- Department of Automotive Science, Kyushu University, Fukuoka 819-0395, Japan
| | - Xiaobin Liang
- Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo 152-8552, Japan
| | - Satoru Yamamoto
- Center for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan
| | - Keiji Tanaka
- Center for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan
- Department of Applied Chemistry, Kyushu University, Fukuoka 819-0395, Japan
| | - Ken Nakajima
- Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo 152-8552, Japan
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7
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Yamaguchi K, Kawaguchi D, Miyata N, Miyazaki T, Aoki H, Yamamoto S, Tanaka K. Kinetics of the interfacial curing reaction for an epoxy-amine mixture. Phys Chem Chem Phys 2022; 24:21578-21582. [PMID: 36093898 DOI: 10.1039/d2cp03394a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A better understanding of the chemical reaction between epoxy and amine compounds at a solid interface is crucial for the design and fabrication of materials with appropriate adhesive strength. Here, we examined the curing reaction kinetics of epoxy phenol novolac and 4,4'-diaminodiphenyl sulfone at the outermost interface using sum-frequency generation spectroscopy, and X-ray and neutron reflectivity in conjunction with a full atomistic molecular dynamics simulation. The reaction rate constant was much larger at the quartz interface than in the bulk. While the apparent activation energy at the quartz interface obtained from an Arrhenius plot was almost identical to the bulk value, the frequency factor at the quartz interface was greater than that in the bulk. These results could be explained in terms of the densification and orientation of reactants at the interface, facilitating the encounter of the reactants present.
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Affiliation(s)
- Ko Yamaguchi
- Department of Applied Chemistry, Kyushu University, Fukuoka, 819-0395, Japan.
| | - Daisuke Kawaguchi
- Department of Applied Chemistry, Kyushu University, Fukuoka, 819-0395, Japan. .,Center for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka, 819-0395, Japan
| | - Noboru Miyata
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, 162-1 Shirakata, Tokai, Naka, Ibaraki, 319-1106, Japan
| | - Tsukasa Miyazaki
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, 162-1 Shirakata, Tokai, Naka, Ibaraki, 319-1106, Japan
| | - Hiroyuki Aoki
- Materials and Life Science Division, J-PARC Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki, 319-1195, Japan.,Institute of Materials Structure Science, High Energy Accelerator Research Organization, 203-1 Shirakata, Tokai, Naka, Ibaraki, 319-1106, Japan
| | - Satoru Yamamoto
- Center for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka, 819-0395, Japan
| | - Keiji Tanaka
- Department of Applied Chemistry, Kyushu University, Fukuoka, 819-0395, Japan. .,Center for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka, 819-0395, Japan
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8
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Ogawa H, Aoki M, Ono S, Watanabe Y, Yamamoto S, Tanaka K, Takenaka M. Spatial Distribution of the Network Structure in Epoxy Resin via the MAXS-CT Method. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:11432-11439. [PMID: 36082480 DOI: 10.1021/acs.langmuir.2c01741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
We have succeeded in visualizing the spatial heterogeneity of the reaction ratio in epoxy resins by combining medium-angle X-ray scattering (MAXS) and computed tomography (CT). The reaction ratio is proportional to the degree of cross-linking between epoxy and amine in epoxy resins. The reaction ratio and its spatial inhomogeneity affect the toughness of epoxy resins. However, there has been no non-destructive method to measure the spatial inhomogeneity of the reaction ratio, although we can measure only the spatially averaged reaction ratio by Fourier-transform infrared spectroscopy (FT-IR). We found that the scattering peak reflected the cross-linking structures in the q region of MAXS and that the peak intensity is proportional to the reaction ratio. By reconstructing CT images from this peak intensity, we visualized the spatial heterogeneity of the reaction ratio. The application of this method may not be limited to epoxy resins but may extend to studying the heterogeneity of cross-linked structures in other materials.
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Affiliation(s)
- Hiroki Ogawa
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
- Riken SPring-8 Center, Sayo-cho, Hyogo 679-5148, Japan
| | - Mika Aoki
- Center for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan
| | - Shunsuke Ono
- School of Computing, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Yuki Watanabe
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
- Riken SPring-8 Center, Sayo-cho, Hyogo 679-5148, Japan
| | - Satoru Yamamoto
- Center for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan
| | - Keiji Tanaka
- Riken SPring-8 Center, Sayo-cho, Hyogo 679-5148, Japan
- Center for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan
- Department of Applied Chemistry, Kyushu University, Fukuoka 819-0395, Japan
| | - Mikihito Takenaka
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
- Riken SPring-8 Center, Sayo-cho, Hyogo 679-5148, Japan
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9
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Shundo A, Yamamoto S, Tanaka K. Network Formation and Physical Properties of Epoxy Resins for Future Practical Applications. JACS AU 2022; 2:1522-1542. [PMID: 35911459 PMCID: PMC9327093 DOI: 10.1021/jacsau.2c00120] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Epoxy resins are used in various fields in a wide range of applications such as coatings, adhesives, modeling compounds, impregnation materials, high-performance composites, insulating materials, and encapsulating and packaging materials for electronic devices. To achieve the desired properties, it is necessary to obtain a better understanding of how the network formation and physical state change involved in the curing reaction affect the resultant network architecture and physical properties. However, this is not necessarily easy because of their infusibility at higher temperatures and insolubility in organic solvents. In this paper, we summarize the knowledge related to these issues which has been gathered using various experimental techniques in conjunction with molecular dynamics simulations. This should provide useful ideas for researchers who aim to design and construct various thermosetting polymer systems including currently popular materials such as vitrimers over epoxy resins.
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Affiliation(s)
- Atsuomi Shundo
- Department
of Applied Chemistry and Center for Polymer Interface and
Molecular Adhesion Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Satoru Yamamoto
- Department
of Applied Chemistry and Center for Polymer Interface and
Molecular Adhesion Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Keiji Tanaka
- Department
of Applied Chemistry and Center for Polymer Interface and
Molecular Adhesion Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
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10
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Kim H, Choi J. Subcontinuum Interpretation of Mechanical Behavior for Cross-Linked Epoxy Networks. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c00593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hongdeok Kim
- Department of Mechanical Design Engineering, Hanyang University, 222 Wangsimni-ro Seongdong-gu, Seoul 04763, Republic of Korea
- Department of Mechanical Engineering, BK21 FOUR ERICA-ACE Center, Hanyang University, 55 Hanyangdaehak-ro, Sangnok-gu, Ansan 15588, Republic of Korea
| | - Joonmyung Choi
- Department of Mechanical Design Engineering, Hanyang University, 222 Wangsimni-ro Seongdong-gu, Seoul 04763, Republic of Korea
- Department of Mechanical Engineering, BK21 FOUR ERICA-ACE Center, Hanyang University, 55 Hanyangdaehak-ro, Sangnok-gu, Ansan 15588, Republic of Korea
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11
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Chiang D, Ouyang H, Yang F, Lee S. An alternative method of solvent‐induced stresses in an elastic thin slab: Moutier theorem. POLYM ENG SCI 2022. [DOI: 10.1002/pen.25916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Douyau Chiang
- Taiwan Instrument Research Institute National Applied Research Laboratories Hsinchu Taiwan
| | - Hao Ouyang
- Department of Materials Science and Engineering National Tsing Hua University Hsinchu Taiwan
| | - Fuqian Yang
- Materials Program, Department of Chemical and Materials Engineering University of Kentucky Lexington Kentucky USA
| | - Sanboh Lee
- Department of Materials Science and Engineering National Tsing Hua University Hsinchu Taiwan
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12
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Wang P, Maeda R, Aoki M, Kubozono T, Yoshihara D, Shundo A, Kobayashi T, Yamamoto S, Tanaka K, Yamada S. In situ transmission electron microscopy observation of the deformation and fracture processes of an epoxy/silica nanocomposite. SOFT MATTER 2022; 18:1149-1153. [PMID: 34989390 DOI: 10.1039/d1sm01452h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Herein, we report the in situ transmission electron microscopy observation of the deformation and fracture processes of an epoxy resin thin film containing silica nanoparticles under tensile strain. Under tensile strain, the dispersed silica nanoparticles in the composite arrest the progress of the crack tip and prevent crack propagation. Concomitantly, the generation and growth of nanovoids at the epoxy matrix/nanoparticle interfaces were clearly observed, particularly in the region near the crack tip. These nanovoids contribute to the dissipation of fracture energy, thereby enhancing the fracture toughness. We also analyzed the local distributions of the true strain and strain rate in the nanocomposite film during tensile testing using the digital image correlation method. In the region around the crack tip, the strain rate increased by 3 to 10 times compared to the average of the entire test specimen. However, the presence of large filler particles in the growing crack suppressed the generation of strain, potentially contributing to hindering crack growth.
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Affiliation(s)
- Pangpang Wang
- Materials Open Lab, Institute of Systems, Information Technologies and Nanotechnologies, Fukuoka 814-0001, Japan.
| | - Ryusei Maeda
- Mechanical Design & Analysis Co., Tokyo 182-0024, Japan
| | - Mika Aoki
- Centre for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan
| | - Tatsuya Kubozono
- Materials Open Lab, Institute of Systems, Information Technologies and Nanotechnologies, Fukuoka 814-0001, Japan.
| | - Daisuke Yoshihara
- Materials Open Lab, Institute of Systems, Information Technologies and Nanotechnologies, Fukuoka 814-0001, Japan.
| | - Atsuomi Shundo
- Department of Applied Chemistry, Kyushu University, Fukuoka 819-0395, Japan
| | | | - Satoru Yamamoto
- Centre for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan
| | - Keiji Tanaka
- Centre for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan
- Department of Applied Chemistry, Kyushu University, Fukuoka 819-0395, Japan
| | - Sunao Yamada
- Materials Open Lab, Institute of Systems, Information Technologies and Nanotechnologies, Fukuoka 814-0001, Japan.
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13
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Shundo A, Aoki M, Yamamoto S, Tanaka K. Effect of Cross-Linking Density on Horizontal and Vertical Shift Factors in Linear Viscoelastic Functions of Epoxy Resins. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c01293] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Atsuomi Shundo
- Department of Automotive Science, Kyushu University, Fukuoka 819-0395, Japan
| | - Mika Aoki
- Center for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan
| | - Satoru Yamamoto
- Center for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan
| | - Keiji Tanaka
- Department of Automotive Science, Kyushu University, Fukuoka 819-0395, Japan
- Center for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan
- Department of Applied Chemistry, Kyushu University, Fukuoka 819-0395, Japan
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14
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Yamamoto S, Kuwahara R, Tanaka K. Dynamic behaviour of water molecules in heterogeneous free space formed in an epoxy resin. SOFT MATTER 2021; 17:6073-6080. [PMID: 34132297 DOI: 10.1039/d1sm00529d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Although an epoxy resin is a stable material, it absorbs moisture over a long period of time, causing deterioration of its material properties. We here applied a full-atomistic molecular dynamics (MD) simulation to study where water molecules exist in an epoxy resin and how they dynamically behave. First, the curing reaction was simulated to obtain a network structure so that the time course of the density, and thereby the free space, in the resin were obtained. The results made it possible to discuss the formation and size distribution of the free spaces which were not connected to each other. Then, a few percent of water were inserted into the free space of the cured epoxy resin to examine the location and dynamics of their molecules. We found that several water molecules were clustered at a preferred site, where hydrogen bonds can be formed with hydroxy, ether and amino groups of the network, in the free space, and they heterogeneously moved from there to other sites.
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Affiliation(s)
- Satoru Yamamoto
- Centre for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan.
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15
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Suzuki Y, Tsuji N, Miyata K, Kano T, Fukao K, Matsumoto A. Characteristic Features of
α
and
β
Relaxations of Poly(diethyl fumarate) as the Poly(substituted methylene). MACROMOL CHEM PHYS 2021. [DOI: 10.1002/macp.202100124] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Yasuhito Suzuki
- Department of Applied Chemistry, Graduate School of Engineering Osaka Prefecture University 1‐1 Gakuen‐cho, Naka‐ku Sakai Osaka 599‐8531 Japan
| | - Nagisa Tsuji
- Department of Applied Chemistry, Graduate School of Engineering Osaka Prefecture University 1‐1 Gakuen‐cho, Naka‐ku Sakai Osaka 599‐8531 Japan
| | - Kairi Miyata
- Department of Physics Ritsumeikan University 1‐1‐1 Noji‐higashi Kusatsu Shiga 525‐8577 Japan
| | - Takahito Kano
- Department of Applied Chemistry, Graduate School of Engineering Osaka Prefecture University 1‐1 Gakuen‐cho, Naka‐ku Sakai Osaka 599‐8531 Japan
| | - Koji Fukao
- Department of Physics Ritsumeikan University 1‐1‐1 Noji‐higashi Kusatsu Shiga 525‐8577 Japan
| | - Akikazu Matsumoto
- Department of Applied Chemistry, Graduate School of Engineering Osaka Prefecture University 1‐1 Gakuen‐cho, Naka‐ku Sakai Osaka 599‐8531 Japan
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Shundo A, Aoki M, Yamamoto S, Tanaka K. Cross-Linking Effect on Segmental Dynamics of Well-Defined Epoxy Resins. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c00513] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Atsuomi Shundo
- Department of Automotive Science, Kyushu University, Fukuoka 819-0395, Japan
- Department of Applied Chemistry, Kyushu University, Fukuoka 819-0395, Japan
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395, Japan
| | - Mika Aoki
- Center for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan
| | - Satoru Yamamoto
- Center for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan
| | - Keiji Tanaka
- Department of Automotive Science, Kyushu University, Fukuoka 819-0395, Japan
- Department of Applied Chemistry, Kyushu University, Fukuoka 819-0395, Japan
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395, Japan
- Center for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan
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Yamamoto S, Tanaka K. Entropy-driven segregation in epoxy-amine systems at a copper interface. SOFT MATTER 2021; 17:1359-1367. [PMID: 33325969 DOI: 10.1039/d0sm01600d] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The composition of an epoxy resin at the interface with the adherend is usually different from that in the bulk due to the enrichment of a specific constituent, a characteristic called interfacial segregation. For better adhesion, it should be precisely understood how epoxy and amine molecules exist on the adherend surface and react with each other to form a three-dimensional network. In this study, the entropic factor of the segregation in a mixture of epoxy and amine at the copper interface before and after the curing reaction is discussed on the basis of a full-atomistic molecular dynamics (MD) simulation. Smaller molecules were preferentially segregated at the interface regardless of the epoxy and amine, and this segregation remained after the curing process. No segregation occurred at the interface for a combination composed of epoxy and amine molecules with a similar size. These findings make it clear that the size disparity between constituents affects the interfacial segregation via the packing and/or translational entropy. The curing reaction was slower near the interface than in the bulk, and a large amount of unreacted molecules remained there. Finally, the effect of molecular shape was also examined. Linear molecules were more likely to segregate than round-shaped ones even though they were similar in volume. We believe that these findings, which are difficult to obtain experimentally, contribute to the understanding of the interfacial adhesion phenomena on a molecular scale.
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Affiliation(s)
- Satoru Yamamoto
- Centre for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan.
| | - Keiji Tanaka
- Centre for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan. and Department of Applied Chemistry, Kyushu University, Fukuoka 819-0395, Japan. and Department of Automotive Science, Kyushu University, Fukuoka 819-0395, Japan and International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395, Japan
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