Curious Carbon Nanotube Property Explained
Carbon nanotubes are long, thin carbon structures with special properties, including great stiffness. In some configurations though, nanotubes will have a stiffness orders of magnitude less than expected, which could affect many applications. Researchers at the Georgia Institute of Technology have recently determined that the cause of this variation is kinks in the nanotubes.
Prior to this study, the variation in stiffness was believed to be due to buckling or growth defects of the nanotubes. After attaching silicon to the tips of the nanotubes and either pulling or compressing them, the Georgia researchers determined that the variations could not be completely explained by the defects. After placing them under an electron microscope and magnifying them by 10,000 times, the researchers have found a new answer. The nanotubes have very small kinks in them, which cause forests of them to be wavy. This waviness allows the nanotubes to act like springs, which is why they are not as stiff when aligned vertically, like trees in a forest.
Though it may seem like the lack of stiffness could be a problems, for some applications, it could be very useful. Carbon nanotubes are excellent thermal conductors, as much as ten times better than copper, and this compliance to pressures should make them ideal for connecting a silicon chip to a heat spreader. As the chip and spreader expand and contract with temperature changes, the nanotubes will not break, and thus continue to conduct heat away from the chips.
Source: Georgia Institute of Technology