Atomistic Investigation of Load Transfer Between DWNT Bundles “Crosslinked” by PMMA Oligomers

Naraghi, Mohammad; Bratzel, Graham; Filleter, Tobin; An, Zhe; Wei, Xiaoding; Nguyen, SonBinh T.; Buehler, Markus J.; Espinosa, Horacio D.

doi:10.1002/adfm.201201358

Cited by 51 publications

(44 citation statements)

References 58 publications

(94 reference statements)

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“…This model has been proven to be a valid and efficient approach to simulate a variety of different configuration of CNT yarns and bundles [26,[31][32][33]. However, for studying larger yarns and fibers containing several nanotubes, the computational cost of full atomistic simulations is extremely high.…”

Section: Coarse-grained MD Simulations Methodsmentioning

confidence: 99%

“…In recent years several approaches have been implemented to enhance the shear interaction between CNTs including chemical functionalization of CNTs [2][3][4], intertube bridging [5,6], manufacturing spring-like carbon nanotube ropes [7], fabricating highly twisted double-helix CNT Yarns [8], fabricating tightly wound helical carbon nanotubes (HCNTs) [9], and wet or dry spinning CNT yarns [10][11][12][13][14][15][16][17][18][19][20]. Among these methods, spinning CNT yarns, either directly from as-grown super-aligned CNTs [13,15,18,21,22] or twisting CNT films [23,24], has been the focus of much attention mainly because of its simplicity and capability of producing long continuous and neat fibers.…”

Section: Introductionmentioning

confidence: 99%

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Mesoscale mechanics of twisting carbon nanotube yarns

2015

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Fabricating continuous macroscopic carbon nanotube (CNT) yarns with mechanical properties close to individual CNTs remains a major challenge. Spinning CNT fibers and ribbons for enhancing the weak interactions between the nanotubes is a simple and efficient method for fabricating high-strength and tough continuous yarns. Here we investigate the mesoscale mechanics of twisting CNT yarns using full atomistic and coarse grained molecular dynamics simulations, considering concurrent mechanisms at multiple length-scales. To investigate the mechanical response of such a complex structure without losing insights into the molecular mechanism, we applied a multiscale strategy. The full atomistic results are used for training a coarse grained model for studying larger systems consisting of several CNTs. The mesoscopic model parameters are updated as a function of the twist angle, based on the full atomistic results, in order to incorporate the atomistic scale deformation mechanisms in larger scale simulations. By bridging across two length scales, our model is capable of accurately predicting the mechanical behavior of twisted yarns while the atomistic level deformations in individual nanotubes are integrated into the model by updating the parameters. Our results focused on studying a bundle of close packed nanotubes provide novel mechanistic insights into the spinning of CNTs. Our simulations reveal how twisting a bundle of CNTs improves the shear interaction between the nanotubes up to a certain level due to increasing the interaction surface. Furthermore, twisting the bundle weakens the intertube interactions due to excessive deformation in the cross sections of individual CNTs in the bundle.

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Section: Coarse-grained MD Simulations Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mesoscale mechanics of twisting carbon nanotube yarns

2015

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“…35 Fitting the results from in situ SEM shear tests on pairs of parallel bundles using the shear lag model reveals an effective interface shear modulus of 10 MPa and shear strength of 350 MPa. 26,29 To demonstrate the model's predictive capabilities, we also modeled the CNT yarns prepared using the "wet-spinning" method at Rice University, 36 here termed "Rice yarns". In the Rice yarns, the "filaments" are individual MWCNTs with an average length of 5 μm and an average diameter of 3.2 nm.…”

Section: Articlementioning

confidence: 99%

Key Factors Limiting Carbon Nanotube Yarn Strength: Exploring Processing-Structure-Property Relationships

et al. 2014

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Studies of carbon nanotube (CNT) based composites have been unable to translate the extraordinary load-bearing capabilities of individual CNTs to macroscale composites such as yarns. A key challenge lies in the lack of understanding of how properties of filaments and interfaces across yarn hierarchical levels govern the properties of macroscale yarns. To provide insight required to enable the development of superior CNT yarns, we investigate the fabrication-structure-mechanical property relationships among CNT yarns prepared by different techniques and employ a Monte Carlo based model to predict upper bounds on their mechanical properties. We study the correlations between different levels of alignment and porosity and yarn strengths up to 2.4 GPa. The uniqueness of this experimentally informed modeling approach is the model's ability to predict when filament rupture or interface sliding dominates yarn failure based on constituent mechanical properties and structural organization observed experimentally. By capturing this transition and predicting the yarn strengths that could be obtained under ideal fabrication conditions, the model provides critical insights to guide future efforts to improve the mechanical performance of CNT yarn systems. This multifaceted study provides a new perspective on CNT yarn design that can serve as a foundation for the development of future composites that effectively exploit the superior mechanical performance of CNTs.

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“…Biological systems such as collagen [41] and nacre [52] have also been shown to benefit from similar mechanisms of shear transfer. There is also some evidence for such interlock in synthetic nanomaterials [68,88,89], but the , where the fibrils are the most compact owing to their uniformity. The addition of larger globules results in less efficient packing.…”

Section: Discussionmentioning

confidence: 99%

Increasing silk fibre strength through heterogeneity of bundled fibrils

Cranford

2013

J. R. Soc. Interface.

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Can naturally arising disorder in biological materials be beneficial? Materials scientists are continuously attempting to replicate the exemplary performance of materials such as spider silk, with detailed techniques and assembly procedures. At the same time, a spider does not precisely machine silk-imaging indicates that its fibrils are heterogeneous and irregular in cross section. While past investigations either focused on the building material (e.g. the molecular scale protein sequence and behaviour) or on the ultimate structural component (e.g. silk threads and spider webs), the bundled structure of fibrils that compose spider threads has been frequently overlooked. Herein, I exploit a molecular dynamics-based coarse-grain model to construct a fully three-dimensional fibril bundle, with a length on the order of micrometres. I probe the mechanical behaviour of bundled silk fibrils with variable density of heterogenic protrusions or globules, ranging from ideally homogeneous to a saturated distribution. Subject to stretching, the model indicates that cooperativity is enhanced by contact through low-force deformation and shear 'locking' between globules, increasing shear stress transfer by up to 200 per cent. In effect, introduction of a random and disordered structure can serve to improve mechanical performance. Moreover, addition of globules allows a tuning of free volume, and thus the wettability of silk (with implications for supercontraction). These findings support the ability of silk to maintain near-molecular-level strength at the scale of silk threads, and the mechanism could be easily adopted as a strategy for synthetic fibres.

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Atomistic Investigation of Load Transfer Between DWNT Bundles “Crosslinked” by PMMA Oligomers

Cited by 51 publications

References 58 publications

Mesoscale mechanics of twisting carbon nanotube yarns

Mesoscale mechanics of twisting carbon nanotube yarns

Key Factors Limiting Carbon Nanotube Yarn Strength: Exploring Processing-Structure-Property Relationships

Increasing silk fibre strength through heterogeneity of bundled fibrils

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