Tensile strength of SWNT

The mechanical properties of various types of carbon nanotubes have been extensively studied by both theoretical and experimental studies. In 1993, Overney et al. firstly calculated the rigidity of short SWNTs and the calculated Young s modulus was estimated to be about 1500 GPa, similar to that of graphite (65). Then a range of studies predicted that the Young s modulus of carbon nanotubes was approximately 1 TPa (66). The tensile strength of SWNTs was also estimated from molecular dynamics simulation to be 150 MPa (67). 

Figure 14.17. Young s modulus and tensile strength of SWNT membrane as a function of irradiation dose.

GPa was obtained by Li et al. Zhu et al. characterized the Young s modulus and tensile strength of SWNT strands and showed that the tensile strength was in the range of 49 to 77 GPa. In their study, the lowest value of elastic modulus of SWNT was only about 100 GPa, owning to internanotube defects. 

It is assumed diat the tensile strength of SWNT sub-bundles follows a two-parameter Weibull distribution, a statistical model based on weakest link concept diat has been widely used for describing the strength of a broad spectrum of engineering materials. The probability of failure of a sub-bundle, Pf, at an applied stress, a, is... 

Figure 14.11. Tensile strength of CNT/Epoxy composites with the 0.5 wt% SWNT loading (a) neat epoxy resin, (b) pristine SWNT/epoxy, (c) cut-SWNT/Epoxy (11).

Tensile strength of 250-300 MPa and moduli of 7-8 GPa for PANi-SWNT composite fibers were approximately two times higher than for neat PANi fiber. The fibers produced were tough enough to be knotted or twisted. Electroactivity was enhanced by the addition of nanotubes, as shown by cyclic voltammetry. 

SWNTs are an important kind of carbon nanotube due to most of their properties change considerably with the (n, m) values, and according to Kataura plot, this dependence is unsteady. Mechanical properties of single SWNTs were predicted remarkable by Quantum mechanics calculations as Young s modulus of 0.64-1 TPa, Tensile Strength of 150-180 GPa, strain to failure of 5-30% while having a relatively low density of 1.4-1.6 g/cm. ... 

The mechanical properties of SWNT reinforced polyurethane (PU) electrospun nanofibers were studied by Sen et al. (89). Stress-strain analysis showed that the tensile strength of the PU/SWNT nanofiber membrane was enhanced by 46% compared to pure PU nanofiber membrane. This value of tensile strength was further increased by 104% for ester functionalized PU/SWNT membranes because of the improved SWNT dispersion and the enhanced PU-SWNT interfacial interaction. 

Because of the difficulties in producing defect-free CNTs, CNT tensile strength is not a single-valued quantity, and has to be described on the basis of probability approach. However, report on the distribution of CNT tensile strength is still absent to date. Here we present die results of a study on direct tensile tests of SWNT bundle and use a two-parameter Weibull distribution to describe its tensile strength distribution. 

Since most SWNTs have diameters in the range of 1 -2 nm, we can expect them to remain cylindrical when they form cables. The stiffness constant of the cable structures will then be the sum of the stiffness constants of the SWNTs. However, just as with MWNTs, the van der Waals binding between the tubes limits tensile strength unless the ends of all the tubes can be fused to a load. In the case of bending, a more exact... 

The first carbon nanotubes discovered in nature, such as those produced in Iijima s experiments, were multiwalled nanotuhes (MWNT). Multiwalled nanotuhes consist of a number of concentric carbon cylinders, a set of tubes nested inside each other. They are somewhat complex systems that are relatively difficult to study. An important step forward in research on carbon nanotuhes occurred in 1993, when scientists learned how to make single-walled nanotubes (SWNT). Using the simpler SWNTs, scientists have learned quite rapidly a great deal about the electrical conductivity, tensile strength, flexibility, toughness, and other physical properties of carbon nanotuhes. 

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