Thermosetting hierarchical composites with high carbon nanotube loadings: En route to high performance

Herceg, Tomi M.; Abidin, Mohamad Jafre Zainol; Greenhalgh, Emile S.; Shaffer, Milo S. P.; Bismarck, Alexander

doi:10.1016/j.compscitech.2016.02.015

Cited by 39 publications

(28 citation statements)

References 89 publications

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“…There was a notable variation in the void volume fraction values, as indicated by the standard deviations in Table . A similar fluctuation is also reported in the literature , and it is associated with defects generated during the infusion process, such as fiber misalignment, entrapped air between fibers or moisture in resin systems .…”

Section: Resultssupporting

confidence: 82%

Porosity Characterization of Carbon Fiber/Epoxy Composite Using Hg Porosimetry and Other Techniques

Monticeli

Montoro

Voorwald

et al. 2020

Polymer Engineering & Sci

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In polymer composites, the porosity acts mainly as a stress concentrator, which has detrimental effects depending on the shape and position of the voids. Also, the presence of voids is detrimental to the mechanical properties, which results in the need for an accurate method for their characterization in terms of morphology, position, and volume fraction. The aim of this study was to establish an appropriate procedure for the measurement of voids in a polymer composite using the mercury porosimetry technique. Data were also collected using the Taguchi approach. Subsequently, the feasibility of applying the Hg porosimetry methodology was confirmed through a comparison with standard techniques. Statistical analysis was used to determine the best Hg porosimetry parameters and pressures between 203 and 231 MPa was found to generate reliable results for the maximum porosity measurement, with no dependence on other parameters. Since the Hg porosimetry, acid digestion, and optical microscopy methods provided porosity results with a statistically significant similarity, it can be concluded that all these methods are feasible for the analysis of voids. Finally, potential benefits of the proposed porosity analysis methodology were highlighted through the characterization of the void volume, position, and morphology. POLYM. ENG. SCI., 60:841–849, 2020. © 2020 Society of Plastics Engineers

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Section: Resultssupporting

confidence: 82%

Porosity Characterization of Carbon Fiber/Epoxy Composite Using Hg Porosimetry and Other Techniques

Monticeli

Montoro

Voorwald

et al. 2020

Polymer Engineering & Sci

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“…Directly mixing CNTs into low viscosity epoxy resin has been a popular route to produce hierarchical CNT-FRP hybrid, but the dramatic increase in viscosity upon addition of CNT and filtering effects by fiber preforms during liquid moulding processes often lead to poor CNT dispersion and incomplete textile impregnation [38]. A compression moulding route using short CNTs and reducing resin flow distance has partially solved this challenge and lead to increases in fracture energy of 24% [39]. Using CNT as sizing material was reported by Warrier et al [36], it showed that the presence of CNTs in the sizing resulted in an increased resistance of crack initiation fracture toughness by +10%, but a lowered crack propagation toughness of −53%.…”

Section: Introductionmentioning

confidence: 99%

Interlaminar toughening in structural carbon fiber/epoxy composites interleaved with carbon nanotube veils

González

Vilatela

2019

Composites Part A: Applied Science and Manufacturing

143

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The susceptibility to delamination is one of the main concerns in fiber reinforced polymer composites (FRPs). This work demonstrates improvements of 60% in Mode-I fracture toughness after integration of thin (~30 micron), continuous veils of carbon nanotubes (CNTs) directly deposited onto carbon fiber fabric as the CNT are drawn from the gas-phase using a semi-industrial process. A combination of optical imaging, scanning electron microscopy and a Raman spectroscopy provide a new rapid tool to unambiguously determine the crack propagation path by simple visual inspection of fracture surface. The results show that interlaminar crossing between CNT veil/CF interfaces is of paramount importance. The crack front alternatingly propagates above and below the CNT-toughened interlayer, significantly improving the fracture toughness of resultant laminates. This mechanism is strongly influenced by the method used to integrate the veils onto the CF. CNT veils directly deposited onto the fabrics as a low-density layer lead to large improvements in interlaminar properties, whereas compact CNT veils densified by solvent exposure prior to their integration in the lay-up act as defects.

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“…The greatest increases in fracture toughness were mostly observed in low performance epoxies, where, as a specific example, the average critical strain energy release rate in Mode I (GIC) of such an epoxy, was increased from 86 to 170 J•m -2 [21]. In contrast, Herceg et al [20] observed a lower GIC improvement (24 %), for a toughened resin, with the addition of 2.7 vol. % CNTs, reaching a value of 840 J•m -2 .…”

Section: Introductionmentioning

confidence: 96%

“…Previous studies have shown that it is possible to increase the fracture toughness of a CF/Epoxy composite by the addition of CNTs, although results vary widely. Several authors dispersed CNTs in epoxy resin and then prepared a CNT/CF/epoxy composite, which exhibited fracture toughness which was up to 98 % [17][18][19][20][21] higher than the reference baseline. The greatest increases in fracture toughness were mostly observed in low performance epoxies, where, as a specific example, the average critical strain energy release rate in Mode I (GIC) of such an epoxy, was increased from 86 to 170 J•m -2 [21].…”

Section: Introductionmentioning

confidence: 99%

Enhancing the fracture toughness of hierarchical composites through amino‒functionalised carbon nanotube webs

Nistal

Falzon

Hawkins

et al. 2019

Composites Part B: Engineering

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The introduction of carbon nanotubes (CNTs) in structural fibre-reinforced polymers, to imbue the composite with multifunctional properties (e.g. enhancing electrical/thermal conductivity, structural health monitoring), has received much attention in recent years. Maintaining, and preferably enhancing, the structural integrity of the composite is imperative. Consequently, strong interfacial bonding between the CNTs and the polymer matrix is sought. If the sought multifunctionality is dependent on specific CNT alignment or orientation, achieved through fragile CNT assemblies, gas-phase chemical functionalisation of the CNT assembly is a viable approach in order to chemically modify the CNT surface without damaging the CNT assembly. This study reports on the gas-phase amino-functionalisation of CNT webs (CNTw) and further explores its influence on the in situ electrical conductivity. The placement of an ethylenediamine-functionalised multilayer CNTw (0.2 g•m-2) between CF plies resulted in a 13 % enhancement in the interlaminar Mode I fracture toughness, while providing an electrical conductivity of 10 3 S•m-1 in the direction of the CNTs within the interleaved CNTw. The effectiveness of the aminofunctionalised CNTw in enhancing the mechanical properties of an epoxy composite is related to an epoxy opening reaction, as demonstrated by Differential Scanning Calorimetry (DSC). Raman and X-ray photoelectron spectroscopies are used to confirm that gas-phase amino-functionalisation does not damage the graphene-based structure and its structural dependent properties.

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Thermosetting hierarchical composites with high carbon nanotube loadings: En route to high performance

Cited by 39 publications

References 89 publications

Porosity Characterization of Carbon Fiber/Epoxy Composite Using Hg Porosimetry and Other Techniques

Porosity Characterization of Carbon Fiber/Epoxy Composite Using Hg Porosimetry and Other Techniques

Interlaminar toughening in structural carbon fiber/epoxy composites interleaved with carbon nanotube veils

Enhancing the fracture toughness of hierarchical composites through amino‒functionalised carbon nanotube webs

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