Future planes, cars may be made of 'buckypaper'

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(Agencies)
Updated: 2008-10-20 15:42

Separately, Japanese physicist Sumio Iijima developed a tube-shaped variation while doing research at Arizona State University.

Researchers at Smalley's laboratory then inadvertently found that the tubes would stick together when disbursed in a liquid suspension and filtered through a fine mesh, producing a thin film - buckypaper.

The secret of its strength is the huge surface area of each nanotube, said Ben Wang, director of Florida State's High-Performance Materials Institute.

"If you take a gram of nanotubes, just one gram, and if you unfold every tube into a graphite sheet, you can cover about two-thirds of a football field," Wang said.

Carbon nanotubes are already beginning to be used to strengthen tennis rackets and bicycles, but in small amounts. The epoxy resins used in those applications are 1 to 5 percent carbon nanotubes, which are added in the form of a fine powder. Buckypaper, which is a thin film rather than a powder, has a much higher nanotube content - about 50 percent.

One challenge is that the tubes clump together at odd angles, limiting their strength in buckypaper. Wang and his fellow researchers found a solution: Exposing the tubes to high magnetism causes most of them to line up in the same direction, increasing their collective strength.

Another problem is the tubes are so perfectly smooth it's hard to hold them together with epoxy. Researchers are looking for ways to create some surface defects - but not too many - to improve bonding.

So far, the Florida State institute has been able to produce buckypaper with half the strength of the best existing composite material, known as IM7. Wang expects to close the gap quickly.

"By the end of next year we should have a buckypaper composite as strong as IM7, and it's 35 percent lighter," Wang said.

Buckypaper now is being made only in the laboratory, but Florida State is in the early stages of spinning out a company to make commercial buckypaper.

"These guys have actually demonstrated materials that are capable of being used on flying systems," said Adams, director of Rice's Richard E. Smalley Institute for Nanoscale Science and Technology. "Having something that you can hold in your hand is an accomplishment in nanotechnology."

It takes upward of five years to get a new structural material certified for aviation use, so Wang said he expects buckypaper's first uses will be for electromagnetic interference shielding and lightning-strike protection on aircraft.

Electrical circuits and even natural causes such as the sun or Northern Lights can interfere with radios and other electronic gear. Buckypaper provides up to four times the shielding specified in a recent Air Force contract proposal, Wang said.

Typically, conventional composite materials have a copper mesh added for lightning protection. Replacing copper with buckypaper would save weight and fuel.

Wang demonstrated this with a composite model plane and a stun gun. Zapping an unprotected part of the model caused sparks to fly. The electric jolt, though, passed harmlessly across another section shielded by a strip of buckypaper.

Other near-term uses would be as electrodes for fuel cells, super capacitors and batteries, Wang said. Next in line, buckypaper could be a more efficient and lighter replacement for graphite sheets used in laptop computers to dissipate heat, which is harmful to electronics.

The long-range goal is to build planes, automobiles and other things with buckypaper composites. The military also is looking at it for use in armor plating and stealth technology.

"Our plan is perhaps in the next 12 months we'll begin maybe to have some commercial products," Wang said. "Nanotubes obviously are no longer just lab wonders. They have real world potential. It's real."

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