<i>In situ</i> transmission electron microscopy observation of the deformation and fracture processes of an epoxy/silica nanocomposite

Wang, Pangpang; Maeda, Ryusei; Aoki, Mizuho; Kubozono, Tatsuya; Yoshihara, Daisuke; Shundo, Atsuomi; Kobayashi, Takaya; Yamamoto, Satoru; Tanaka, Keiji; Yamada, Sunao

doi:10.1039/d1sm01452h

Cited by 10 publications

(23 citation statements)

References 25 publications

(29 reference statements)

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“…In the current work, we seek to characterize the local mechanical response at the interface of silica nanoparticles filled into a fully amine-cured epoxy resin. For this epoxy nanocomposite system, a recent study using an in situ transmission electron microscopy (TEM) method has observed the generation and development of nanovoids surrounding silica nanoparticles during tensile deformation and fracture tests, which nicely supports the concept related to the debonding process at the interface as the prominent mechanism for the enhancement of the epoxy toughness induced by nanoparticles. More importantly, the accumulated nanovoids at the silica/epoxy interface, as revealed in this study, strongly suggest a difference in the physical properties between the interfacial layer and bulk matrix, although a quantitative comparison is yet to be obtained.…”

Section: Introductionsupporting

confidence: 66%

“…This confirms that the 20 nm soft layer shown in Figure e, which was characterized by using a relatively smaller probe with a radius of 7 nm, represents the intrinsic behavior of the silica/epoxy interface, rather than due to the tip convolution effect under the interaction with the nanoparticle. In fact, several techniques have been used to characterize the mechanical properties of interfacial polymers surrounding a solid nanoparticle. ,, In a recent report, Wang and co-workers applied a TEM technique to visualize nanovoids at the silica/epoxy interface for the HDGEBA/CBMA nanocomposites under tensile deformation. Nanovoids surrounding the silica were not directly observed in TEM images for an undeformed sample.…”

Section: Resultsmentioning

confidence: 99%

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Unraveling Nanoscale Elastic and Adhesive Properties at the Nanoparticle/Epoxy Interface Using Bimodal Atomic Force Microscopy

Nguyen

Shundo

Liang

et al. 2022

ACS Appl. Mater. Interfaces

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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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Section: Introductionsupporting

confidence: 66%

Section: Resultsmentioning

confidence: 99%

Unraveling Nanoscale Elastic and Adhesive Properties at the Nanoparticle/Epoxy Interface Using Bimodal Atomic Force Microscopy

Nguyen

Shundo

Liang

et al. 2022

ACS Appl. Mater. Interfaces

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“…226,227 Recently, Yamada, Kobayashi and co-workers reported in situ transmission electron microscopic (TEM) observation of the deformation and fracture processes for an epoxy resin film containing silica nanoparticles under the tensile process. 228 Dispersed silica nanoparticles in the composite arrested the progress of the crack tip and prevented 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.…”

Section: Fracture Toughnessmentioning

confidence: 99%

Section: Network and Physical Propertiesmentioning

confidence: 99%

“…Recently, Yamada, Kobayashi and co-workers reported in situ transmission electron microscopic (TEM) observation of the deformation and fracture processes for an epoxy resin film containing silica nanoparticles under the tensile process . Dispersed silica nanoparticles in the composite arrested the progress of the crack tip and prevented crack propagation.…”

Section: Network and Physical Propertiesmentioning

confidence: 99%

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Network Formation and Physical Properties of Epoxy Resins for Future Practical Applications

Shundo

Yamamoto

Tanaka

2022

JACS Au

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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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Exploring the Impact of Molecular Structure on Curing Kinetics: A Comparative Study of Diglycidyl Ether of Bisphenol A and F Epoxy Resins

Shundo,

Thao Phan,

Aoki

et al. 2024

J. Phys. Chem. B

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Epoxy resins are essential for various applications, and their properties depend on the curing reactions during which epoxy and amine compounds form the network structure. We here focus on how the presence or absence of two methyl groups in common epoxy bases, diglycidyl ether of bisphenol A and F (4,4′-DGEBA and 4,4′-DGEBF), affects the curing kinetics. The chemical reactions of both 4,4′-DGEBA and 4,4′-DGEBF, when cured with the same amine, were monitored by Fourier-transform infrared (FT-IR) spectroscopy and differential scanning calorimetry (DSC). Despite no difference in the reactivity of epoxy groups between 4,4′-DGEBA and 4,4′-DGEBF, the initial curing reaction was slower for the latter. This delay for the 4,4′-DGEBF system was attributed to intermolecular stacking, which hindered the approach of unreacted epoxy groups to amino groups and vice versa. This conclusion was drawn from the results obtained through ultraviolet (UV) spectroscopy, wide-angle X-ray scattering (WAXS), density functional theory (DFT) calculation, and all-atom molecular dynamics (MD) simulation.

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In situ transmission electron microscopy observation of the deformation and fracture processes of an epoxy/silica nanocomposite

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...

Cited by 10 publications

References 25 publications

Unraveling Nanoscale Elastic and Adhesive Properties at the Nanoparticle/Epoxy Interface Using Bimodal Atomic Force Microscopy

Unraveling Nanoscale Elastic and Adhesive Properties at the Nanoparticle/Epoxy Interface Using Bimodal Atomic Force Microscopy

Network Formation and Physical Properties of Epoxy Resins for Future Practical Applications

Exploring the Impact of Molecular Structure on Curing Kinetics: A Comparative Study of Diglycidyl Ether of Bisphenol A and F Epoxy Resins

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