Monday, November 19, 2007

Superstrong Carbon-Nanotube Fibers

Continued from page 1

By Mason Inman

"The most up-front application is for body armor," he says. "It looks promising compared to commercially available fibers." But whether or not it will work for body armor "no one will really know until we make enough fiber to make a fabric and shoot a bullet at it," Windle says. A recent computer modeling study suggests that bullets would bounce off a carbon-nanotube fabric just six layers thick.

Edwin Thomas, a professor of materials science and engineering at MIT, says that if tests showed that such fabric really did repel bullets, "you've got a showstopper, and it's going to be in body armor soon." But materials often don't cope well when hit with sudden forces as opposed to slower tugging, he adds. "Nobody knows about carbon nanotubes at high rates of strain, because no one has checked."

Another application could be oil drilling. "Since carbon-nanotube fibers are not only strong, but also resist heat and corrosion, they could be used in drill bits or pipes to cope with these extreme environments," says Thomas.

Thomas cautions, however, that Windle and his colleagues got their best results for fibers about one millimeter long, apparently because the longer the strand, the more likely it is to contain small chunks of carbon and other defects that weaken it. "Tweaking the processing--the wind-up speed and the acetone treatment--isn't going to change the carboneous particles," Thomas says. "They've got to go back into the chemical synthesis" to address that.

"For the army to be interested in it, they'd want to have kilometers of it," he says. Nonetheless, the new results give him "lots of hope."