Superhot nanotubes gain strength as they stretch

May 11, 2006

2 min read

A single-walled carbon nanotube 75-nm long can stretch to 84 nm before it breaks. New calculations show that heating the nanotube more than 3,600°F makes it 2.8 times stronger than it was in its original form.

Researchers at Lawrence Livermore National Laboratory, Boston College, and the Massachusetts Institute of Technology have devised a high-temperature (3,600°F) strengthening technique that boosts the strength of single-walled carbon nanotubes by a factor of nearly 2.8. The super-strain can be used to tune electronic properties of the carbon nanotubes for applications in microelectronics, said Yinmin (Morris) Wang of LLNL's Materials Science and Technology Div.

A typical carbon nanotube is 10,000 times smaller than a human hair and can stretch to 15% longer than its original length before it fails. But at temperatures in the range of 3,600°F the nanotube diameter shrinks from 12 to 8 nm as it stretches to more than 2.8 times its original length before breaking. "This kind of intense superelongation (stretching and reduction in diameter) in a carbon nanotube is unprecedented," says Wang. At such high temperatures, the nanotube appears to be completely pliable, resulting in a superplastic deformation that would otherwise be impossible at low temperatures.

Wang hopes the team's surprising discovery of nanotube superplasticity will encourage further investigation of mechanical and electronic behavior at high temperatures. "The tubes may find uses as reinforcement agents in ceramics or other nanocomposites for high-temperature applications," he says.