Tensile strength nanotubes

The tensile strength of carbon nanotubes has been determined to be over 50 times that of high-carbon steel (Yu et al., 2000). The strength of the bond structure in carbon nanotubes... 

Carbon nanotubes conduct electricity because of the extended network of delocalized ir-bonds that runs from one end of the tube to the other. Along the long axis of the tube, their conductivity is high enough to be considered metallic. The tubes are very strong, and their tensile strength parallel to the axis of the tube is the greatest of any material that has... 

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. 

Polymer nanocomposites with medium density polyethylene were reported with a variety of fluorinated and un-fluorinated nanotubes (37). The nanocomposites consisting of 1 wt% F-SWNT-C H (fluorinated and surface treated nanotubes) nanotubes showed an increase in tensile strength by 52.4%, modulus by 15.9% and elongation by 18.9% as compared to the pure polymer. The composites with 1 wt% F-SWNT-CnH23 (fluorinated and surface treated nanotubes) had an increase of 28.3% in modulus as compared to the pure polymer. The tensile strength also increased from 4.33 MPa for the pure polymer to 5.01 Mpa for the nanocomposite, the elongation at... 

In the epoxy nanocomposites containing untreated as well as maleic anhydride grafted nanotubes (51), the tensile strength was observed to increase by 50% at 1 wt% of the modified nanotubes, whereas the untreated nanotubes led to only a slight increase in the tensile strength which subsequently decreased on further addition of these pristine nanotubes. The tensile modulus of the nanocomposites was observed... 

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). 

Kwon et al. compared WPU/MWNT with WPU/nitric acid treated multiwalled carbon nanotube (A-CNT) composites (20). The tensile strength and modulus of the WPU/A-CNT composites were higher than those of the WPU/MWNT composites with the same CNT content. The better mechanical properties of WPU / A-CNT composites can perhaps be attributed to higher content of polar groups of A-CNTs thus inducing higher interfacial interactions between A-CNTs and WPU chains. 

---