Stress transfer in multi-walled carbon nanotubes

Zalamea, Luis; Kim, Hyonny; Pipes, R. Byron

doi:10.1016/j.compscitech.2007.03.011

Cited by 60 publications

(50 citation statements)

References 20 publications

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“…The value of  interwall was stated in earlier reports of the literature [40][41][42]. Finally,  interface is assumed to 20 MPa, as described previously [39].…”

Section: Estimation Of Multiple Fracture Of Cnt Under Tensile Loadingmentioning

confidence: 99%

Nanoscopic observations for evaluating the failure process of aligned multi-walled carbon nanotube/epoxy composites

Tsuda

Ogasawara

Moon

et al. 2013

Composites Science and Technology

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This study examined the nanoscopic damage progression of aligned multi-walled carbon nanotubes (CNT) / epoxy composites under tensile loading using transmission electron microscopy (TEM). Aligned CNT/epoxy composite films (30 micro meter thickness) were processed using a forestdrawn aligned CNT sheet and hot-melt prepreg method. Four film specimens, respectively subjected to tensile stress of 0 MPa, 45 MPa, 95 MPa and 110 MPa, were prepared. After tensile loading, each specimen was machined until the thickness became about 100 nm using a focused ion beam milling machine (FIB) for TEM observations. Damage of three kinds, i.e. CNT break derived from the disordered CNT structures around metallic catalyst, sword-in-sheath type CNT break, and several patterns of interfacial debonding, was observed clearly. The broken CNTs and interfacial debonding per unit area were counted from TEM photographs. Results show that broken CNTs and interface debonding increased considerably at 95-110 MPa, which suggests multiple fracture of CNT under tensile loading. The CNT length at the failure stress (110 MPa) was approximately 45 μm. Estimated values from the strength of CNTs resemble those from macroscopic stress-strain behavior.Nanoscopic observations for evaluating the failure process of aligned multi-walled carbon nanotube / epoxy composites AbstractThis study examined the nanoscopic damage progression of aligned multi-walled carbon nanotubes (CNT) / epoxy composites under tensile loading using transmission electron microscopy (TEM). Aligned CNT/epoxy composite films (30 m thickness) were processed using a

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“…The value of  interwall was stated in earlier reports of the literature [40][41][42]. Finally,  interface is assumed to 20 MPa, as described previously [39].…”

Section: Estimation Of Multiple Fracture Of Cnt Under Tensile Loadingmentioning

confidence: 99%

Nanoscopic observations for evaluating the failure process of aligned multi-walled carbon nanotube/epoxy composites

Tsuda

Ogasawara

Moon

et al. 2013

Composites Science and Technology

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“…They do not have appeared to have recognized the extraction of k i as a parameter in the first experimental half of the paper, where k i is measured independently of the dispersion and polymer/nanotube interactions. k i is then used to predict the effective modulus of a nanotube, taking into account its full cross-sectional area, based upon the model of Zalamea et al [3] Lin and Wang [2] also question the assumption that the Raman band shift rates depend linearly upon the Young's modulus of the nanotube. Lin and Wang argue that whilst it has been shown that this linear dependence exists for carbon fibres, it might not apply to single crystals such as nanotubes.…”

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confidence: 99%

Response to “Comment on the Effect of Stress Transfer Within Double‐Walled Carbon Nanotubes upon Their Ability to Reinforce Composites”

et al. 2010

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We are pleased that our paper on the stress transfer within double-walled carbon nanotubes (DWNTs) in composites [1] is being read and promoting discussion in the field, but we do not agree with most of the comments by Lin and Wang upon the Communication.[2] We feel that they have missed some of the key concepts in the paper and, although they state that the data should be reinterpreted, they do not suggest an alternative approach.Lin and Wang [2] state that we have ''attempted to indicate that the capability of the outer wall of taking on the load transferred from the polymer matrix is reduced due to the poor wall-to-wall stress transfer''. However, we discuss clearly in our paper that they are two stress-transfer processes in the DWNTs, the polymer/outer-wall interface (k 0 ) and the wall/wall interface (k i ). We do not ever relate k 0 to the wall/wall interface, as Lin and Wang imply in their comment. This confusion between the two interfaces by Lin and Wang may help understanding why they are not satisfied with the paper. They do not have appeared to have recognized the extraction of k i as a parameter in the first experimental half of the paper, where k i is measured independently of the dispersion and polymer/nanotube interactions. k i is then used to predict the effective modulus of a nanotube, taking into account its full cross-sectional area, based upon the model of Zalamea et al. [3] Lin and Wang [2] also question the assumption that the Raman band shift rates depend linearly upon the Young's modulus of the nanotube. Lin and Wang argue that whilst it has been shown that this linear dependence exists for carbon fibres, it might not apply to single crystals such as nanotubes. This is a valid argument, but Ferrari et al. [4] have shown recently that this linear assumption also applies to graphene, which is the ultimate carbon single crystal.Throughout the paper we have assume that the atomic stiffness of a given wall is that of graphene. Thus, if everything was perfect in the composite, we would expect to see a similar band shift in each wall to that in graphene ($0.05 cm À1 GPa per %). However, we do not see such a shift. The reason for the low shift rate in the outer walls is due to the nonperfect polymer/ nanotube interface, which includes poor dispersion. We acknowledge in the paper that this poor dispersion is the reason why the DWNT outer walls have a lower shift rate than the walls of the single-walled carbon nanotubes (SWNTs). However, the fact we see a shift rate less than expected for a graphene-like lattice implies that the stress is being transferred poorly into the lattice; hence the effective modulus of this wall is reduced. We assume that the atomic stiffness is the same in both the inner and outer walls of the nanotubes. Therefore the difference in the Raman band shift of the inner and outer walls must be related to having less stress present in the inner wall than the outer. This difference in stress for a given strain allows us to measure directly the efficiency of the stress transfer ac...

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“…Radii, R i.1 R i.2n are outermost and innermost radii of CNTs associated with n layers, respectively. In the study, individual CNT thickness, p, is selected as 0.14 nm [5,10,14,15] and the gap between two adjacent layers is s = 0.34 nm [9]. The inner radius of the innermost layer, n, is firmly chosen as R i.2n = 5 nm.…”

Section: Introductionmentioning

confidence: 99%

“…As a result, a development of a new theoretical model for load transfer in the composites associated with numerous CNT layer numbers is critical in understanding the potential of CNT composites. Answers to some critical issues by the new model such as the effect of CNT layer numbers and aspect ratio [5,9] are indispensable in applications of CNT-reinforced composites. Furthermore, it is expected that the theoretical model can provide a comprehensive investigation on effects of matrix properties on load transfer since the thickness and Young's modulus of matrix and shear modulus magnitude of interface between matrix and reinforcement would provide a more effective tool in understanding load transfer in the composites.…”

Section: Introductionmentioning

confidence: 99%

A studying on load transfer in carbon nanotube/epoxy composites under tension

Việt

Wang

Kuo

2017

Journal of Modeling in Mechanics and Materials

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Abstract:The shear-lag model is developed to study the effect of geometry and material properties of epoxy and carbon nanotubes on load transfer in carbon nanotube/epoxy composites under tension. The results from proposed shear-lag model are validated by finite element method and the Haque's model. Results show that the aspect ratio of the half-length to the outer radius of carbon nanotubes and their layer number have significant influence on load transfer in the composites. On the other hand, this research reveals new findings, which are not reported in other previous works. That is, no noticeable influences of the epoxy Young's modulus and the interface shear modulus between epoxy matrix and carbon nanotube layers are found on load transfer in terms of the saturated stress length. In addition, the carbon nanotube volume percentage is found not affecting the load transfer. This research presents a better understanding on mechanical properties of carbon nanotube/epoxy composites.

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Stress transfer in multi-walled carbon nanotubes

Cited by 60 publications

References 20 publications

Nanoscopic observations for evaluating the failure process of aligned multi-walled carbon nanotube/epoxy composites

Nanoscopic observations for evaluating the failure process of aligned multi-walled carbon nanotube/epoxy composites

Response to “Comment on the Effect of Stress Transfer Within Double‐Walled Carbon Nanotubes upon Their Ability to Reinforce Composites”

A studying on load transfer in carbon nanotube/epoxy composites under tension

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