The tensile strengths of individual multiwalled carbon nanotubes (MWCNTs) were measured with a “nanostressing stage” located within a scanning electron microscope. The tensile-loading experiment was prepared and observed entirely within the microscope and was recorded on video. The MWCNTs broke in the outermost layer (“sword-in-sheath” failure), and the tensile strength of this layer ranged from 11 to 63 gigapascals for the set of 19 MWCNTs that were loaded. Analysis of the stress-strain curves for individual MWCNTs indicated that the Young's modulus E of the outermost layer varied from 270 to 950 gigapascals. Transmission electron microscopic examination of the broken nanotube fragments revealed a variety of structures, such as a nanotube ribbon, a wave pattern, and partial radial collapse.

https://science.sciencemag.org/content/sci/287/5453/637.full.pdf

Strength and breaking mechanism of multiwalled carbon nanotubes under tensile load

https://www.bc.edu/content/dam/files/schools/cas_sites/physics/pdf/Ren/p85.pdf

Advances in the science and technology of carbon nanotubes and their composites: a review

Department of Materials Science, University of Patras, 26504 Rio Patras, Greece, Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vass. Constantinou Avenue, 116 35 Athens, Greece, Institut de Biologie Moleculaire et Cellulaire, UPR9021 CNRS, Immunologie et Chimie Therapeutiques, 67084 Strasbourg, France, and Dipartimento di Scienze Farmaceutiche, Universita di Trieste, Piazzale Europa 1, 34127 Trieste, Italy

Chemistry of Carbon Nanotubes

Small but strong: A review of the mechanical properties of carbon nanotube–polymer composites

Nanotubes from Carbon.

We report the observation of single nanotube fragmentation, under tensile stresses, using nanotube-containing thin polymeric films. Similar fragmentation tests with single fibers instead of nanotubes are routinely performed to study the fiber-matrix stress transfer ability in fiber composite materials, and thus the efficiency and quality of composite interfaces. The multiwall nanotube-matrix stress transfer efficiency is estimated to be at least one order of magnitude larger than in conventional fiber-based composites.

Stress-induced fragmentation of multiwall carbon nanotubes in a polymer matrix

Recent experimental and theoretical results [1 ‐ 9] suggest that carbon nanotubes hold great promise as a possible reinforcing phase in composite materials of a new kind. Such developments still present, however, enormous practical challenges, especially when probing the properties of individual nanotubes [3,10‐ 12]. The mechanical stiffness and strength of carbon nanotubes are expected to be very high [2,4,8]. Also, breaks in nanotubes, either in tension or compression, were rarely observed following specimen cutting [9,12], which was taken to imply that nanotubes have very high strength [9]. It is remarkably difficult to directly measure the mechanical properties of single nanotubes. The stiffness of carbon nanotubes was recently measured by a thermal vibration technique [3] and Young’s modulus was reported to be in the 1 ‐ 5 TPa range. (The modulus of diamond, one of the stiffest known materials, is 1.2 TPa [13].) Here we report deformation modes resulting from the embedment of the tubes in a polymer matrix, and a first estimation of the strength of carbon nanotubes under compressive stresses. Multiwall carbon nanotubes, prepared by a carbon-arc discharge method, were sonicated in ethanol and subsequently dried and dispersed on a glass surface. An epoxy resin (Araldite LY564, Ciba-Geigy) was used as embedding medium. The liquid polymer mixture was carefully spread onto the dried nanotube-containing graphite powder using a blade. The mixture was polymerized in a closed mold for five days at room temperature. This

Buckling and Collapse of Embedded Carbon Nanotubes

Micro-Raman spectroscopy is used to monitor the cooling-induced compressive deformation of carbon nanotubes embedded in an epoxy matrix. Young’s modulus of single- and multiwall nanotubes may then be derived from a concentric cylinder model for thermal stresses, using the D*-band shift for each tube type. The resulting values of the elastic moduli are in very good agreement with predicted theoretical values, and with the published experimental data set of Treacy et al., Nature (London) 381, 678 (1996).

O. Lourie

Papers

Stress-induced fragmentation of multiwall carbon nanotubes in a polymer matrix

Buckling and Collapse of Embedded Carbon Nanotubes

Evaluation of Young's Modulus of Carbon Nanotubes by Micro-Raman Spectroscopy