Mechanics of vitrimer particle compression and fusion under heat press

Yu, Luxia; Sun, Xiaohao; Zhang, Wei; Long, Rong

doi:10.1016/j.ijmecsci.2021.106466

Cited by 14 publications

(7 citation statements)

References 67 publications

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“…Pressure, temperature, and processing time can synergistically affect the degree of powder fusion and hence the quality (e.g., porosity and mechanical properties) of the resulting composite . In general, higher pressure can improve contact between powder particles and between powder and carbon fibers, thereby reducing pore defects in composites, while higher temperature and longer processing time can promote interfacial healing between powder particles and stress relaxation within each powder particle …”

Section: Resultsmentioning

confidence: 52%

“…29 In general, higher pressure can improve contact between powder particles and between powder and carbon fibers, thereby reducing pore defects in composites, while higher temperature and longer processing time can promote interfacial healing between powder particles and stress relaxation within each powder particle. 33 To examine the effects of processing conditions, we performed uniaxial tensile tests of the composite samples prepared under different pressure, temperature, and processing time (see Table S1). Under 140 °C and 1.25 MPa, 2 min is the minimum time needed to obtain composite samples with a translucent matrix.…”

Section: Resultsmentioning

confidence: 99%

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Rapid Fabrication of Fiber-Reinforced Polyimine Composites with Reprocessability, Repairability, and Recyclability

Lei

Sun

et al. 2021

ACS Appl. Polym. Mater.

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Polyimine is a type of covalent adaptable networks, known as vitrimer, endowed with dynamic imine bonds that can reversibly break and reform upon either heat or moisture. Its low topology freezing transition temperature (∼130 °C) and responsiveness to moisture make polyimine suitable for recycling, reprocessing, and repairing under mild processing conditions. Here, we demonstrate the rapid fabrication of carbon fiber-reinforced polyimine composites and their unique properties. Using a powder-based compression molding method, we are able to fabricate carbon fiber-reinforced polyimine within ∼4 min. The resulting composites exhibit similar mechanical properties as the samples prepared through much slower liquid-based impregnation method (>24 h). We also demonstrate in situ, mold-free repair of polyimine composites with a curved surface at low temperature and pressure (∼75 °C, implemented by a handheld iron for 5 min). The malleability, weldability, and full recyclability of polyimine composites fabricated by the powder-based method are also demonstrated. These unique properties offer great promise for expanding the manufacturing capability and extending the service life of fiber-reinforced composites.

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Section: Resultsmentioning

confidence: 52%

Section: Resultsmentioning

confidence: 99%

Rapid Fabrication of Fiber-Reinforced Polyimine Composites with Reprocessability, Repairability, and Recyclability

Lei

Sun

et al. 2021

ACS Appl. Polym. Mater.

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“…The mechanism is to connect vitrimer particles together in the form of covalent bonds by stimulating bond exchange reactions at the contact interface. [ 46 ] Further, it is possible to produce a composite laminate by directly hot‐pressing three layers of vitrimer powders embedded with two layers of carbon fiber sheets under the same processing condition (Figure 6c). Figure 6d shows the SEM images of the cross section of the composite prepared by solid‐state fabrication.…”

Section: Resultsmentioning

confidence: 99%

Tough Epoxy Vitrimer with Hybrid Networks and Its Applications in Reprocessable Composites

Chen

Jin

et al. 2023

Adv Eng Mater

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Progress in the ever‐growing vitrimer chemistry opens up great opportunities for a sustainable society by producing reprocessable thermosets. However, most vitrimers suffer from the conflict between mechanical performance and dynamic reactivity, hindering the development of industrial applications. Herein, a facile but universal material design strategy is proposed to yield tough epoxy vitrimers while preserving excellent reprocessability. Copolymerization and bond exchange reactions can build covalent bridges between heterogeneous polymer networks, thus leading to a hybrid dynamic covalent polymer network containing hard and soft segments. Tailorable mechanical and thermal properties are obtained by controlling the ratio of hard‐to‐soft components. The resulting epoxy vitrimer can balance strength and stretchability while exhibiting brittle‐to‐ductile transformation in tensile tests. Enhanced fracture toughness is achieved compared to both pristine hard and soft vitrimers. The resulting vitrimers exhibit excellent processability and potential applications in composite fabrication, welding and reshaping, and multiple shape memory functions. This work presents a feasible approach to satisfying the demands of mechanical performance and dynamic reactivity in the design of epoxy vitrimers. The material design principle will be applicable to a wide range of vitrimer systems to pursue desirable properties.

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“…The particle coalescence process predicted by Long et al in a modeling study of vitrimer particle coalescence behavior, reports that interfaces between particles undergo regimes of elevated stress as compared to the bulk particle and eventually result in coalescence. 36 Initially, cross-link density may be low between particles, but at sufficient lengths of time, the increase in crosslinking across the interface resulted in modulus values near that of the bulk particle and ultimately resulted in a homogeneous surface. It is also important to recall that coalescence at the glass−particle interface occurred faster than through the bulk, so the modulus through the bulk may not be homogeneous at the same time as the surface.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Tunable Surfaces and Films from Thioester Containing Microparticles

Martinez

Cox

Darabi

et al. 2022

ACS Appl. Mater. Interfaces

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Reported here, thioester containing microparticles were designed with 40% excess thiol to enable thiol–thioester exchange to facilitate the formation of cohesive films from the particles. A thiol-Michael dispersion polymerization was used to generate thioester containing microparticles with a diameter of 4.0 ± 0.4 μm. The particles were then swollen with a base at varying concentrations to activate the thiol–thioester exchange and subsequently compressed between two glass slides. Resultant films were characterized over time with profilometry and atomic force microscopy (AFM) to infer particle coalescence at different catalyst loadings and times. Tensile tests were performed confirming the structural integrity of the particle-based films. Furthermore, microparticles were welded to a nondynamic network demonstrating feasibility in potential applications to generate materials containing differing mechanical properties. Being able to control the functionality of particles, and thus mechanical properties of the resultant films, is also important for applications in coatings, adhesives, and 3D printing where spatial patterning or selective material property control is needed.

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Mechanics of vitrimer particle compression and fusion under heat press

Cited by 14 publications

References 67 publications

Rapid Fabrication of Fiber-Reinforced Polyimine Composites with Reprocessability, Repairability, and Recyclability

Rapid Fabrication of Fiber-Reinforced Polyimine Composites with Reprocessability, Repairability, and Recyclability

Tough Epoxy Vitrimer with Hybrid Networks and Its Applications in Reprocessable Composites

Tunable Surfaces and Films from Thioester Containing Microparticles

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