Nanotubes Gain Strength as They Stretch

Photo: View of carbon nanotubes

A single-walled carbon nanotube heated to more than 3,600 degrees Fahrenheit became nearly 280 percent stronger than it was in its original form, and its diameter shrunk by 15 times. The discovery has implications in strengthening ceramic and other nanocomposites at high temperatures and is useful in tuning electronics.
Carbon Nanotubes

“The super-strain we discovered can be used to tune the electronic properties of carbon nanotubes for their applications in microelectronics,” said Yinmin Wang of Lawrence Livermore National Laboratory’s (LLNL) Materials Science and Technology Division.

A typical carbon nanotube can be stretched to 15 percent longer than its original length before it fails. But in the high-temperature experiments, the heated nanotube was able to stretch to more than 280 percent of its original length before it broke. The researchers took a 24-nanometer piece of nanotube and stretched it to 91 nanometers before it failed, while the diameter was reduced by 15 times from 12 to 0.8 nanometers.

“This kind of intense stretching and reduction in diameter in a carbon nanotube is unprecedented,” Wang said. “This super-elongation is due to a full plastic deformation that occurs at high temperatures.”

Under such high temperatures, the nanotube appears to be completely pliable, resulting in a superplastic deformation that would otherwise be impossible at low temperatures.

“Our surprising discovery of superplasticity in nanotubes should encourage the investigation of their mechanical and electronic behavior at high temperatures,” Wang said. “The tubes may find uses as reinforcement agents in ceramics or other nanocomposites for high-temperature applications.”; Source: DOE/Lawrence Livermore National Laboratory