roperties amazing MWNT

Researchers from the CNRS, in collaboration with a British team showed that carbon nanotubes with double walls exhibited novel properties of resistance to high pressures. Their results, published in the journal Physical Review Letters, have important applications in various fields.
The scientists have sought to understand the mechanical behavior of the sheets relative to each other. They subjected carbon nanotubes with double walls to hydrostatic pressure of 10,000 to 100,000 times atmospheric pressure, and analyzed their behavior by an optical technique for probing the mechanical properties of materials through their vibrations. They show that the two sides of the nanotubes did not behave the same way under the pressure, while the outer wall behaves like a single wall nanotubes single wall, the wall seems to undergo internal part of pressure. These experiments prove that the various walls of carbon nanotubes are not in strong interaction and behave in a mechanical point of view independently of one another. This behavior is specific to carbon nanotubes and is not in the graphite, which is the macroscopic equivalent. This fundamental research on nanotubes with double walls, the easiest system to understand the mechanical behavior of layers relative to each other, is an important step in modeling the mechanical properties of multi-walled nanotubes. Their great strength is the ideal tool for applications in certain areas of nanotechnology that involve the use of high pressure. double-walled nanotubes represent a high security since the accidental breaking of an inner wall is not necessarily transmitted to all walls of the nanotube, as would likely occur if all the leaves were also sensitive to pressure.

• Important Note:

French and U.S. physicists have discovered beads hanging on carbon nanotubes, like beads of dew on a cobweb. They show the role of liquid carbon nanotube growth in the hitherto assumed to be formed from carbon vapor.
So far, all the mechanisms put forward involves a vapor phase: we imagined that the carbon anode is vaporized under the effect of arc (5000 ° C) and was crystallized at the cathode. In the study published by Science, the scientists showed that the formation mechanism of carbon nanotubes involves melted. The chemical composition analysis revealed that this was pure carbon ion and amorphous. In addition, the ball looked like leftover liquid.
Through this work, the researchers had the opportunity to study the behavior of liquid carbon (very poorly known because it evaporates very quickly) and see that it is comparable to that of other liquids.Under the scenario they have developed, the nanotubes are formed, like most of the crystals from a liquid phase cooling. The arc creates a drop in the carbon anode, which evaporates until the pressure of gas leaving the carbon drop equals the helium pressure in the oven, thus stabilizing the liquid carbon. The drop then continues to cool by convection and its edges become more and more viscous. Inside, the liquid cools slowly. Nanotubes crystallize it, by sticking to each other to form a needle. Carbon viscous, which covers the needle nanotubes, then formed glass beads on carbon nanotubes.