Effect of scale and surface chemistry on the mechanical properties of carbon nanotubes‐based composites

Lachman, Noa; Harel, Yifat; Green, Adam; Iuster, Noa; Lellouche, Jean‐Paul; Wagner, H. Daniel

doi:10.1002/polb.23085

Cited by 10 publications

(3 citation statements)

References 21 publications

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“…The second mechanism is associated with the CNTs and involves their ''pull out'' (or debonding) from the DX MG matrix, or from entanglements during strain, both of which would dissipate energy and oppose crack propagation. A pull out mechanism has been postulated to be responsible for the improved toughness of CNT elastomer composites; 64 however, that mechanism is new for CNT hydrogel composites. A third mechanism is decreased inter-MG covalent linking due to co-location of CNTs and vinyl groups from the MGs at the MG interface.…”

Section: Discussionmentioning

confidence: 99%

A study of conductive hydrogel composites of pH-responsive microgels and carbon nanotubes

et al. 2016

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Conductive gel composites are attracting considerable attention because of their interesting electrical and mechanical properties. Here, we report conductive gel composites constructed using only colloidal particles as building blocks. The composites were prepared from mixed dispersions of vinyl-functionalised pH-responsive microgel particles (MGs) and multi-walled carbon nanotubes (CNTs). MGs are crosslinked pH-responsive polymer colloid particles that swell when the pH approaches the pKa of the particles. Two MG systems were used which contained ethyl acrylate (EA) or methyl acrylate (MA) and around 30 mol% of methacrylic acid (MAA). The MA-based MG is a new pH-responsive system. The mixed MG/CNT dispersions formed thixotropic physical gels. Those gels were transformed into covalent interlinked electrically conducting doubly crosslinked microgel/CNT composites (DX MG/CNT) by free-radical reaction. The MGs provided the dual roles of dispersant for the CNTs and macro-crosslinker for the composite. TEM data showed evidence for strong attraction between the MG and the CNTs which facilitated CNT dispersion. An SEM study confirmed CNT dispersion throughout the composites. The mechanical properties of the composites were studied using dynamic rheology and uniaxial compression measurements. Surprisingly, both the ductility and the modulus of the gel composites increased with increasing CNT concentration used for their preparation. Human adipose-derived mesenchymal stem cells (AD-MSCs) exposed to DX MG/CNT maintained over 99% viability with metabolic activity retained over 7 days, which indicated non-cytotoxicity. The results of this study suggest that our approach could be used to prepare other DX MG/CNT gel composites and that these materials may lead to future injectable gels for advanced soft-tissue repair.

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Section: Discussionmentioning

confidence: 99%

A study of conductive hydrogel composites of pH-responsive microgels and carbon nanotubes

et al. 2016

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“…Thostenson et al among others 10 explain that CNTs increase toughness through energy dissipation, not through plastic deformation, but rather crack bridging and pullout, with demonstrated gains in fracture toughness and fatigue life. [11][12][13] Several groups have seen a transition from tough to brittle fracture for some ductile polymers under increasing CNT content, suggesting diminishing returns with added CNT filler content. 14 All explorations on CNTbased polymer nanocomposites explore randomly oriented reinforcement with limited control towards homogeneous dispersion.…”

Section: Introductionmentioning

confidence: 99%

Fracture Toughness of Aligned Carbon Nanotube Polymer Nanocomposites

Wicks

Vazquez

Wardle

2015

56th AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

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Aligned carbon nanotubes (CNTs) are being investigated for application to numerous material disciplines including structural composite materials due to their unique scaledependent physical properties. Prior work on nanoengineered composite architectures demonstrated improved interlaminar fracture toughness was dependent on epoxy type. In this work, we seek to understand the reinforcement mechanisms of aligned CNTs in a polymer matrix in the absence of fibers, of aligned polymer nanocomposites in different epoxy types. Preliminary investigations were performed using single edge notch beam specimens to isolate the fracture toughness of small CNT nanocomposites, and the mechanisms of reinforcement can be elucidated through tight control over CNT alignment and loading epoxy. While crack initiation off a sharpened precrack are unchanged with added aligned CNTs, an increase in fracture surface area and added crack arrest capability reveal mechanisms by which CNTs can add absorb energy and increase toughness post crack initiation. NomenclatureA-PNC = aligned CNT polymer nanocomposite CNT = carbon nanotube CVD = chemical vapor deposition DCB = double cantilever beam K Ic = Mode I critical stress intensity FFRP = fuzzy fiber reinforced plastic FRP = fiber reinforced plastic PNC = polymer nanocomposite RVE = representative volume element SEM = scanning electron microscope SENB = single edge notch beam V f = volume fraction I. Introduction arbon nanotubes (CNTs) are being investigated for application to numerous material disciplines including structural composite materials due to their unique scale-dependent and intrinsic physical properties. 1 With high specific strength and stiffness and nanoscale dimensions, 2 aligned CNTs are an attractive candidate for incorporation into laminated composites, including interlaminar reinforcement. Mechanical properties that are limited by the matrix-dominated interlaminar region in traditional composites are typically reinforced through changing the fiber architecture as in stitching/weaving or modifying the matrix properties through tougheners and additives. 3 Nanoengineered architectures integrate both approaches, reinforcing the interlaminar regions with nanoscale fibers that provide toughening through nanoscale fiber pull-out 4 and modifying matrix properties. As realized in Fuzzy Fiber Reinforced Plastics (FFRP) where aligned CNTs are grown radially on advanced fibers, the demonstrated improvements in Mode I toughness are shown to dependent on the type of epoxy and the CNT length through a combination of driving fracture towards or away from fiber surfaces and increasing fracture surface area. 5,6 The work here aims to decouple the multiscale effects in interlaminar toughening by determining the toughness of the

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“…Thostenson et al among others 9 explain that CNTs increase toughness through energy dissipation, not through plastic deformation, but rather crack bridging and pullout, with demonstrated gains in fracture toughness and fatigue life. [10][11][12] Several groups have seen a transition from tough to brittle fracture for some ductile polymers under increasing CNT content, suggesting diminishing returns with added CNT filler content. 13 All explorations on CNTbased polymer nanocomposites explore randomly oriented reinforcement with limited control towards homogeneous dispersion.…”

Section: Introductionmentioning

confidence: 99%

Fracture Toughness of Aligned Carbon Nanotube Polymer Nanocomposites for the Reinforcement of Hierarchical Composite Materials

Wicks

Wardle

2014

55th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

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Aligned carbon nanotubes (CNTs) are being investigated for application to numerous material disciplines including structural composite materials due to their unique scaledependent physical properties. Nanoengineered architectures called Fuzzy Fiber Reinforced Plastics (FFRP) have been developed, where CNTs are grown radially on advanced fibers and extend into inter and intralaminar spaces. The aligned CNT forests induce a swelling of the tows and cloth causing fibers to spread apart, and the demonstrated improvements in Mode I toughness could be attributed to changes in matrix properties, interlaminar region morphology due to the swelling of the plies, or a combination of both. The work here aims to decouple the two effects by determining the toughness of the matrix region in the absence of fibers, employing aligned-CNT polymer nanocomposites with relevant CNT loadings (volume fractions). A single edge notch beam specimen has been demonstrated to isolate the fracture toughness of such aligned-CNT reinforced polymer nanocomposites. Nomenclature CNT= carbon nanotube CVD = chemical vapor deposition DCB = double cantilever beam KIc = Mode I critical stress intensity FFRP = fuzzy fiber reinforced plastic FRP = fiber reinforced plastic PNC = polymer nanocomposite RVE = representative volume element SEM = scanning electron microscope SENB = single edge notch beam Vf = volume fraction I. Introduction arbon nanotubes (CNTs) are being investigated for application to numerous material disciplines including structural composite materials due to their unique scale-dependent and intrinsic physical properties. 1 With high specific strength and stiffness and nanoscale dimensions, 2 aligned CNTs are an attractive candidate for incorporation into laminated composites, including interlaminar reinforcement. Mechanical properties that are limited by the matrix-dominated interlaminar region in traditional composites are typically reinforced through changing the fiber architecture as in stitching/weaving or modifying the matrix properties through tougheners and additives. 3 Nanoengineered architectures integrate both approaches, as realized in Fuzzy Fiber Reinforced Plastics (FFRP) where aligned CNTs are grown radially on advanced fibers and extend into inter and intralaminar spaces as shown in Figure 1. 4,5 The aligned-CNT forests induce a swelling of the cloth tows causing fibers to spread out and apart, and the demonstrated improvements in Mode I toughness could be attributed to either the changes in matrix properties or the morphological change of the interlaminar region due to the swelling of the plies, or a complex combination of both. The work here aims to decouple the two effects by determining the toughness of the matrix

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Effect of scale and surface chemistry on the mechanical properties of carbon nanotubes‐based composites

Cited by 10 publications

References 21 publications

A study of conductive hydrogel composites of pH-responsive microgels and carbon nanotubes

A study of conductive hydrogel composites of pH-responsive microgels and carbon nanotubes

Fracture Toughness of Aligned Carbon Nanotube Polymer Nanocomposites

Fracture Toughness of Aligned Carbon Nanotube Polymer Nanocomposites for the Reinforcement of Hierarchical Composite Materials

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