Microstructure evolution and self-assembling of CNT networks during mechanical stretching and mechanical properties of highly aligned CNT composites

Jolowsky, Claire; Sweat, Rebekah; Park, Jin Gyu; Hao, Ayou; Liang, Richard

doi:10.1016/j.compscitech.2018.04.003

Cited by 54 publications

(59 citation statements)

References 24 publications

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“…The imbibition kinetics through the network (captured by rate R capi ) depend on the characteristics of the CNT network, including the CNT diameter distribution, packing density, and alignment. In this study, we focused on aligned sheets of multi‐walled CNTs (MWCNTs) obtained by a floating catalyst CVD method [ 22 ] (Figure 1c). The generally hydrophobic nature of MWCNTs [ 23 ] and their resulting stronger affinity with the organic solution than with the aqueous solution informed the sequential order of the liquid phases in which the CNT sheets were immersed.…”

Section: Resultsmentioning

confidence: 99%

“…These voids result from the manufacturing technique used to form the CNT sheets. In the floating catalyst CVD method, the CNTs form an aerogel‐like “sock” which collapses prior to mechanical collection from the furnace; this resulting CNT sheet is then aligned by wet‐stretching [ 22 ] to form the CNT ribbons used as a starting material in this work. As the sock forms, it typically has a highly entangled web of CNTs on the outer surface, and a low‐density, low‐entanglement core where the carrier gas mainly flows.…”

Section: Resultsmentioning

confidence: 99%

“…After synthesis, the CNT sheets are liquid‐saturated and stretched by ≈35%, resulting in a final CNT Herman orientation factor of 0.7. [ 22 ] The sheets also have 5–10wt% amorphous carbon and 10–20 wt% residual catalyst. Particular attention was given to confirming the absence of carboxylic acid groups at the surface of the CNTs, as such functionalities could react with the diamine monomer molecules and result in covalent bonding of the polymer chains with the CNTs.…”

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

In Situ Interfacial Polymerization: A Technique for Rapid Formation of Highly Loaded Carbon Nanotube‐Polymer Composites

Chazot

Jons

Hart

2020

Adv Funct Materials

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Composites of polymers and organized carbon nanotube (CNT) networks have been proposed as next-generation lightweight structural materials, yet polymer infiltration of CNT networks often results in stress-concentrating heterogeneities, due to local CNT aggregation or incomplete infiltration. Herein, it is demonstrated that dense CNT-polymer composites with tailored polymer distribution can be obtained by interfacial polymerization (IP), performed in situ within CNT networks. Three regimes of the in situ interfacial polymerization (ISIP) process are identified: a reaction-limited regime where the polymer forms beads on the CNTs; a uniformly-filled regime with polymer throughout the CNT network; and a transport-limited regime with polymer only near the outer surface of the network. Uniform polyamide-CNT composite sheets obtained by this method have a Young's modulus of 31 GPa and a tensile strength of 776 MPa, which is a twofold increase compared to the pristine CNT sheets. Premature failure of the composites is attributed to large voids in the pristine CNT sheets, suggesting that further improved mechanical properties can be achieved with a more homogeneous CNT network. Nevertheless, the rapid rate and overall controllability of ISIP suggest its viability for formation of polymers within CNT networks via roll-to-roll methods.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

In Situ Interfacial Polymerization: A Technique for Rapid Formation of Highly Loaded Carbon Nanotube‐Polymer Composites

Chazot

Jons

Hart

2020

Adv Funct Materials

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“…This SEM is a multi-technique dual beam (electron and Ga ion) field-emission scanning electron microscope (FESEM) with a spatial resolution for imaging of 0.7 nanometers. Fiber tows were spread on a flat substrate and fixed with a diluted resin solution; then, thin lamellae were prepared using a FIB [ 24 ]. For the TEM observations, both cross-sectional and longitudinal directions of the CF samples were prepared and mounted on the TEM lift-out grid.…”

Section: Methodsmentioning

confidence: 99%

A Digital Twin Approach to a Quantitative Microstructure-Property Study of Carbon Fibers through HRTEM Characterization and Multiscale FEA

2020

Self Cite

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Microstructures of typical carbon fibers (CFs) from polyacrylonitrile (PAN) and pitch-based precursors were studied using a novel digital twin approach with individual carbon fibers for a local crystal scale model. The transmission electron microscopy (TEM) samples were prepared using a focused-ion beam (FIB) for both longitudinal and transverse directions of carbon fibers. Measurements of the crystal size and orientation were estimated from X-ray scattering. TEM imaging of graphitic packing facilitated further comprehension of associations between processing and final material properties, which could enable customization of microstructures for property targets. Then the detailed microstructural information and their X-ray scattering properties were incorporated into the simulation model of an individual carbon fiber. Assuming that graphene properties are the same among different forms of carbon fiber, a reasonable physics-based explanation for such a drastic decrease in strength is the dislocations between the graphitic units. The model reveals critical defects and uncertainty of carbon fiber microstructures, including skin/core alignment differences and propagating fracture before ultimate failure. The models are the first to quantify microstructures at the crystal scale with micromechanics and to estimate tensile and compressive mechanical properties of carbon fiber materials, as well as potentially develop new fundamental understandings for tailoring carbon fiber and composites properties.

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“…Even though the flCNT-flCNT contact was enhanced by the flattening and stacking, the TEM-observed fracture surfaces showed intrastack sliding in addition to complete stack pullout. A follow-up study by Jolowsky et al [8] provided a pathway to scale the flCNT composite fabrication method to macro-scale panels with excellent mechanical properties. Patil et al [9] reported the polymer/flCNT interfacial characteristics for two polyimide systems at the nanoscale using Molecular Dynamics (MD) techniques.…”

Section: Introductionmentioning

confidence: 99%

Prediction of Interfacial Properties of High-Performance Polymers and Flattened CNT-Reinforced Composites using Molecular Dynamics

Deshpande

Radue

Gaikwad

et al. 2021

Preprint

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Microstructure evolution and self-assembling of CNT networks during mechanical stretching and mechanical properties of highly aligned CNT composites

Cited by 54 publications

References 24 publications

In Situ Interfacial Polymerization: A Technique for Rapid Formation of Highly Loaded Carbon Nanotube‐Polymer Composites

In Situ Interfacial Polymerization: A Technique for Rapid Formation of Highly Loaded Carbon Nanotube‐Polymer Composites

A Digital Twin Approach to a Quantitative Microstructure-Property Study of Carbon Fibers through HRTEM Characterization and Multiscale FEA

Prediction of Interfacial Properties of High-Performance Polymers and Flattened CNT-Reinforced Composites using Molecular Dynamics

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