Ultra-tough and in-situ repairable carbon/epoxy composite with EMAA

Loh, Thomas W.; Ladani, Raj B.; Orifici, Adrian C.; Kandare, Everson

doi:10.1016/j.compositesa.2020.106206

Cited by 17 publications

(12 citation statements)

References 45 publications

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“…Some pioneering studies carried out by Pingkarawat et al [ 18 , 19 , 20 , 28 , 29 , 30 ] reported that EMAA can improve the critical strain energy release rate modes I ( G IC ) and II ( G IIC ) by 60–650% and 35–200%, respectively, with healing efficiencies of 40–300% for G IC and 47–130% for G IIC . Similar explorations conducted by Varley et al [ 14 , 26 ], Meure et al [ 21 , 25 ], Yang et al [ 31 ], Ladani et al [ 32 , 33 ], and Loh et al [ 34 , 35 ] have also found that increments of 13–400% for G IC and 20–76% for G IIC , as well as healing efficiencies of 45–410% for G IC , 40–80% for G IIC , and 36–109% for interlaminar shear strength ( ILSS ) were respectively obtained. Nevertheless, the literature also revealed that the integration of less strong EMAA into composite laminates will decrease the in-plane strength (by 25–50%) [ 19 , 28 ] and ILSS (by 22–35%) [ 22 , 36 ], which is the biggest challenge for structural applications.…”

Section: Introductionsupporting

confidence: 70%

“…The bubbles helped the molten EMAA to flow into the delamination crack under internal pressure and then bound with the fractured surfaces. In addition, the -COOH groups in EMAA can also react with the -NH 2 groups in CNTs [ 22 , 34 ], which further increases the crosslinking density between different components, resulting in more energy consumption of the extracted NH 2 -CNTs during crack growth (subfigures in Figure 5 (f 2 ,g 3 )). In conclusion, all these factors together led to an improvement in the delamination resistance and high self-healing efficiency.…”

Section: Resultsmentioning

confidence: 99%

“…Previous studies have demonstrated that poly[ethylene-co-(methacrylic acid)] (EMAA) is an excellent self-healing thermoplastic copolymer with the advantages of a high thermal expansion coefficient, covalently crosslinking with epoxy, and pressure delivery self-healing mechanism [ 17 , 18 , 19 , 20 , 21 ]. Traditionally, EMAA has been incorporated into thermosetting epoxy matrices of composite laminates in the form of particles [ 18 , 19 , 20 , 22 ], membranes [ 23 , 24 ], meshes [ 25 , 26 , 27 ], stitches [ 28 , 29 , 30 , 31 ], or woven filaments [ 32 , 33 , 34 , 35 ], showing good delamination resistance and high recovery of interlaminar fracture toughness. Some pioneering studies carried out by Pingkarawat et al [ 18 , 19 , 20 , 28 , 29 , 30 ] reported that EMAA can improve the critical strain energy release rate modes I ( G IC ) and II ( G IIC ) by 60–650% and 35–200%, respectively, with healing efficiencies of 40–300% for G IC and 47–130% for G IIC .…”

Section: Introductionmentioning

confidence: 99%

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Electrothermally Self-Healing Delamination Cracks in Carbon/Epoxy Composites Using Sandwich and Tough Carbon Nanotube/Copolymer Interleaves

Ouyang

Liu²,

Wu³

2022

Polymers

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Herein, two sandwich and porous interleaves composed of carbon nanotube (CNT) and poly(ethylene-co-methacrylic acid) (EMAA) are proposed, which can simultaneously toughen and self-heal the interlaminar interface of a carbon fiber-reinforced plastic (CFRP) by in situ electrical heating of the CNTs. The critical strain energy release rate modes I (GIC) and II (GIIC) are measured to evaluate the toughening and self-healing efficiencies of the interleaves. The results show that compared to the baseline CFRP, the CNT-EMAA-CNT interleaf could increase the GIC by 24.0% and the GIIC by 15.2%, respectively, and their respective self-healing efficiencies could reach 109.7–123.5% and 90.6–91.2%; meanwhile, the EMAA-CNT-EMAA interleaf can improve the GIC and GIIC by 66.9% and 16.7%, respectively, and the corresponding self-healing efficiencies of the GIC and GIIC are 122.7–125.9% and 93.1–94.7%. Thus, both the interleaves show good toughening and self-healing efficiencies on the interlaminar fracture toughness. Specifically, the EMAA-CNT-EMAA interleaf possesses better multi-functionality, i.e., moderate toughening ability but notable self-healing efficiency via electrical heating, which is better than the traditional neat EMAA interleaf and oven-based heating healing method.

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Section: Introductionsupporting

confidence: 70%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electrothermally Self-Healing Delamination Cracks in Carbon/Epoxy Composites Using Sandwich and Tough Carbon Nanotube/Copolymer Interleaves

Ouyang

Liu²,

Wu³

2022

Polymers

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“…Via in situ electrical‐heating, the T‐joint peeling experimental results demonstrated that the initial ultimate load of epoxy composites was restored to 107%, and the EMAA/CNT porous film was able to accommodate both the structural integrity and the repeated repairs of local cracks. Loh et al 42 developed a new multi‐functional composite by integrating the mendable EMAA filaments into the carbon fabric in co‐braiding manner. The developed composites were found to possess higher fracture toughness and in situ delamination‐repair capability by comparing with the baseline composites.…”

Section: Introductionmentioning

confidence: 99%

Low‐velocity impact and self‐healing behavior of CFRP laminates with poly(ethylene‐co‐methacrylic acid) filament reinforcement

Zhang

Tie

2023

Polymer Composites

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An experimental study is performed to explore the low‐velocity impact (LVI) and self‐healing behavior of carbon‐fiber‐reinforced‐polymer (CFRP) laminates reinforced by thermoplastic poly(ethylene‐co‐methacrylic acid) (EMAA) filaments. Firstly, differential scanning calorimetry (DSC), thermos‐gravimetric analysis (TGA) and dynamic mechanical analysis (DMA) are used to determine the process parameters. Thereafter, the unreinforced laminates and EMAA reinforced laminates are prepared via phased hot‐processing curing process. The LVI tests with four energy levels (5, 15, 25 and 35 J) are then carried out on the two types of specimens. In these energy cases, the peak‐force values of the reinforced specimens are 2.2%, 1.9%, 2.3% and 7.5% higher than those of the unreinforced ones, while the energy‐absorption‐rate values of the reinforced ones are 6.02%, 3.53%, 4.24% and 2.32% lower. The comparisons demonstrate the impact‐resistance enhancement of EMAA. Moreover, multiple LVI tests are performed on the unhealed and healed specimens. In 15 and 25 J cases, around 6.92% higher peak load and 4.58% lower absorbed energy are observed within the healed specimens, which is attributed to the healing effect. The healing mechanism is investigated by utilizing attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR), scanning electron microscope (SEM) and optical microscope (OM) technologies. It reveals that EMAA flows into the delaminations and cracks during the healing process, and thus accomplishing self‐healing behavior effectively.

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“…On the other hand, thermoplastics readily undergo polymer chain reentanglement beyond their melting point (T m ). Poly(ethylene-comethacrylic acid) (EMAA)-a commodity copolymer thermoplastichas been shown to exhibit self-healing in neat films 37 and also deployed in various forms (e.g., particles, fibers) within FRP composites to restore mechanical performance via thermal remending [38][39][40][41][42] . However, to date, researchers have only realized FRP repair either ex situ (i.e., in an oven) or above T g of the composite matrix; the former eliminates the ability to achieve in-service repair, while the latter compromises structural function during healing and elicits irreversible changes.…”

mentioning

confidence: 99%

Prolonged in situ self-healing in structural composites via thermo-reversible entanglement

et al. 2022

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Natural processes continuously degrade a material’s performance throughout its life cycle. An emerging class of synthetic self-healing polymers and composites possess property-retaining functions with the promise of longer lifetimes. But sustained in-service repair of structural fiber-reinforced composites remains unfulfilled due to material heterogeneity and thermodynamic barriers in commonly cross-linked polymer-matrix constituents. Overcoming these inherent challenges for mechanical self-recovery is vital to extend in-service operation and attain widespread adoption of such bioinspired structural materials. Here we transcend existing obstacles and report a fiber-composite capable of minute-scale and prolonged in situ healing — 100 cycles: an order of magnitude higher than prior studies. By 3D printing a mendable thermoplastic onto woven glass/carbon fiber reinforcement and co-laminating with electrically resistive heater interlayers, we achieve in situ thermal remending of internal delamination via dynamic bond re-association. Full fracture recovery occurs below the glass-transition temperature of the thermoset epoxy-matrix composite, thus preserving stiffness during and after repair. A discovery of chemically driven improvement in thermal remending of glass- over carbon-fiber composites is also revealed. The marked lifetime extension offered by this self-healing strategy mitigates costly maintenance, facilitates repair of difficult-to-access structures (e.g., wind-turbine blades), and reduces part replacement, thereby benefiting economy and environment.

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Ultra-tough and in-situ repairable carbon/epoxy composite with EMAA

Cited by 17 publications

References 45 publications

Electrothermally Self-Healing Delamination Cracks in Carbon/Epoxy Composites Using Sandwich and Tough Carbon Nanotube/Copolymer Interleaves

Electrothermally Self-Healing Delamination Cracks in Carbon/Epoxy Composites Using Sandwich and Tough Carbon Nanotube/Copolymer Interleaves

Low‐velocity impact and self‐healing behavior of CFRP laminates with poly(ethylene‐co‐methacrylic acid) filament reinforcement

Prolonged in situ self-healing in structural composites via thermo-reversible entanglement

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