Further research also was reported in the same article regarding the effect of electron irradiation on these materials. One would think that irradiation would degrade the atomic structure of the material, but the researchers found the opposite.
"Irradiating a multiwalled carbon nanotube with an intense electron beam actually forms bonds among the shells of the tube. This is like combining multiple nanotubes into one to form a stronger structure," said lead author Bei Peng, who recently received his doctoral degree from Northwestern under Espinosa's supervision.
This phenomenon also has been theorized in the past, and the research confirms that the properties of multiwalled nanotubes can easily and controllably be altered by electron irradiation.
The irradiation work was supplemented by detailed atomistic modeling. Using computer simulations of the atomic structure of the nanotubes, the team of researchers was able to isolate the mechanism of strengthening due to irradiation.
"The same procedure used to strengthen individual multiwalled nanotubes by irradiation may also be used to link together individual nanotubes into a bundle," said Mark Locascio, a doctoral student co-author of the paper.
This mechanism of crosslinking is a promising method for creating much larger nanotube-based structures. When nanotubes are packed together, they typically have very weak interactions along their surfaces; a spun nanotube rope would not be nearly as strong as its nanoscale constituents. However, irradiation may be the key to improving these interactions by inducing covalent bonds between tubes. If the properties of nanotubes can be scaled up to macroscale ropes and fibers, they may become a viable option for any high-strength applic
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