New Nanotube show different mechanical properties

29 April 2008

A group of researchers from US along with the experts from Brazil have discovered that carbon nanotube sheets can have different mechanical properties if stretched or uniformly compressed. These useful mechanical properties can be beneficial for various applications as making artificial muscles, sensors, composites and gaskets.

In general materials if pulled in one direction contract laterally or get thinner, however specially designed carbon nanotube sheets behave differently. These nanotube sheets or buckypaper can increase in width on stretching and can also increase in length and width once uniformly compressed.

Dr. Ray H. Baughman and his team of researchers at the University of Texas at Dallas have created nanotube sheets by drying fiber slurry having mixtures of single-walled (SWNTs) and multi-walled (MWNTs) carbon nanotubes. Researchers claimed that by increasing multi-walled carbon nanotubes, the Poisson’s Ratio turns from a positive value of 0.06 to negative value of 0.20. Poisson’s Ratio is defined as the ratio of percent lateral contraction to the applied stretch.

Researchers found that the sharp transition in Poisson’s Ratio surprising and subsequently found that nanotubes containing SWNTs and MWNTs have 1.6 times higher stretch to weight ratio, 2.4 percent higher toughness and 1.4 times higher modulus to weight ratio than the sheets containing SWNTs or MWNTs alone. The research paper is recently published in Journal Science of April 25 issue.

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