Chain diffusion based framework for modeling the welding of vitrimers

An, Le; Shi, Qian; Jin, Chenyu; Zhao, Wenzhe; Wang, T.J.

doi:10.1016/j.jmps.2022.104883

Cited by 22 publications

(8 citation statements)

References 54 publications

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“…This is possibly because excess press force squeezes out the depolymerized network and further prevents depolymerized chain diffusion at the welding interface. Therefore, increasing the press force does not significantly promote the welding efficiency, which is completely different from the reported results, indicating that press force accelerates welding without surface depolymerization [19,20].…”

Section: The Influences Of Welding Conditionscontrasting

confidence: 97%

“…Yu et al [17][18][19] used a constant press force of kPa to weld and recycle soft epoxy vitrimer, and the recycled material restored the mechanical properties to the level of the fresh material. For hard epoxy vitrimer, the welding pressure increased to MPa [20]. Luzuriaga et al ground the epoxy vitrimer composites into powder and obtained the second-generation composites under 20 MPa pressure [1].…”

Section: Introductionmentioning

confidence: 99%

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Facile Surface Depolymerization Promotes the Welding of Hard Epoxy Vitrimer

Zhao

2022

Materials

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Welding via bond exchange reactions has provided advances in obtaining high-quality joining performance. However, the reported welding method requires a relatively high press force, and challenges are still encountered in welding hard vitrimer. In this work, a facile surface depolymerization strategy was introduced to weld high-performance epoxy vitrimer. The vitrimers were firstly dissolved into ethylene glycol for depolymerization based on the solvent-assisted bond exchange reactions. Then, the depolymerized vitrimers were welded under heat and press force. The effect of the depolymerizing time, welding pressure, welding temperature and welding time on the welding strength were further investigated. It was found that there were optimal values for the depolymerizing time, welding pressure, and welding temperature, respectively, for the welding strength, while the welding strength increased with increasing welding time. Through facile surface degradation, the welding pressure was highly reduced, while the welding strength was increased. With surface depolymerization, the welding strength was 1.55-times higher, but the magnitude of press force was 1/1000-times than that with no surface depolymerization. It is elucidative that surface depolymerization can be used to weld hard vitrimer composites alongside reducing the press force effectively.

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Section: The Influences Of Welding Conditionscontrasting

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Facile Surface Depolymerization Promotes the Welding of Hard Epoxy Vitrimer

Zhao

2022

Materials

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“…For the CANs, there are two types of relaxation times, i.e., τ normals = τ normalb + τ normalc where τ b and τ c represent the BER time and diffusion time, respectively. The chain diffusivity is related to its diffusion distance and diffusion time, e.g., l 0 2 = D coop τ c . Based on eqs and , Yu et al proposed the expression for relaxation time (τ b ) as, τ normalb ≈ τ 0 0.25em exp ( E 0 R T + γ V 0 V − k so Δ V t − V 0 ) where τ 0 is the diffusion time for the monomer, and E 0 is the energy barrier of BER.…”

Section: Theoretical Framework Of Interfacial Weldingmentioning

confidence: 99%

“…The chain diffusivity is related to its diffusion distance and diffusion time, e.g., l 0 2 = D coop τ c . 51 Based on eqs 5a and 5b, Yu et al proposed the expression for relaxation time (τ b ) as, 52 i k j j j j j y…”

Section: Constitutive Stress−elongation Ratiomentioning

confidence: 99%

Self-Toughening and Interfacial Welding of Covalent Adaptable Networks Undergoing Hydro-Chemo-Mechanical Coupling

Zhang

Shi

et al. 2022

Macromolecules

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Thermosetting epoxy polymers can be designed with recycling, remodeling, and repairing properties owing to the special bond exchange reactions (BERs) in their covalent adaptable networks (CANs). However, the mechanisms behind their complex coupling of hydrodynamic diffusion, molecular reactions, and topological network structure changes have not been fully understood. In this paper, a hydro-chemo-mechanical coupling model is developed to describe self-toughening mechanisms of thermosetting epoxy polymers, wherein the CANs cooperatively undergo the combined processes of hydrodynamic diffusion, chemical BERs, and mechanical topology entanglements. Based on free volume theory and rubber elasticity theory, an extended phantom network model is developed to investigate the synergistic effects of hydrodynamics, BERs, and mechanical topology on interfacial welding and self-toughening behaviors of the CANs. A constitutive stress−strain relationship is further developed to understand the self-toughening mechanisms of CANs undergoing the hydro-chemo-mechanical coupling. Finally, the effectiveness of the proposed model is verified using the results obtained from the experiments and finite element analysis.

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“…[8] Vitrimers combine the advantages of both thermoset and thermoplastic and display "3R" properties: reprocessability, reparability, and recyclability. [9,10] Vitrimers have great potential in composites, [11][12][13] shapeshifting, [14][15][16][17][18] polymer welding, [19][20][21] 3D printing, [22][23][24][25] and other functional applications. [26][27][28] More importantly, the dynamic covalent polymer network in vitrimer allows interfacial bond exchange reactions to improve the compatibility between vitrimers and other organic or inorganic materials.…”

Section: Introductionmentioning

confidence: 99%

Tough and Thermostable Polybutylene Terephthalate (PBT)/Vitrimer Blend with Enhanced Interfacial Compatibility

Chen

Cui

Jin

et al. 2023

Macromol. Rapid Commun.

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Polymer blending is an efficient way to obtain extraordinary polymeric materials. However, once permanently cross‐linked thermosets are involved in blending, there are challenges in designing and optimizing the structures and interfacial compatibility of blends. Vitrimer with dynamic covalent polymer networks provides an innovative opportunity for blending thermoplastics and thermosets. Herein, a reactive blending strategy is proposed to develop thermoplastic‐thermoset blend with enhanced compatibility on the basis of dynamic covalent chemistry. Specifically, polybutylene terephthalate (PBT) and polymerized epoxy vitrimer can be directly melt blended to obtain tough and thermostable blends with desirable microstructures and interfacial interaction. Bond exchange facilitates the grafting of PBT and epoxy vitrimer chains, thus enhancing the interfacial compatibility and thermal stability of blends. The obtained blend balances the strength and stretchability of PBT and epoxy vitrimer, resulting in enhanced toughness. This work offers a new way of designing and fabricating new polymeric materials by blending thermoplastics and thermosets. It also suggests a facile direction towards upcycling thermoplastics and thermosets.

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Chain diffusion based framework for modeling the welding of vitrimers

Cited by 22 publications

References 54 publications

Facile Surface Depolymerization Promotes the Welding of Hard Epoxy Vitrimer

Facile Surface Depolymerization Promotes the Welding of Hard Epoxy Vitrimer

Self-Toughening and Interfacial Welding of Covalent Adaptable Networks Undergoing Hydro-Chemo-Mechanical Coupling

Tough and Thermostable Polybutylene Terephthalate (PBT)/Vitrimer Blend with Enhanced Interfacial Compatibility

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