The problems with carbon nanotubes have been making them into usable "macromaterials," says Jennifer Chase Fielding, a materials research engineer with another ARFL/RX branch—Composites & Hybrid Materials—which studies fibers and paper made from carbon nanotubes and nanofibers for ways to leverage their highly thermally and electrically conductive properties.
In addition to studying Nanocomp's technology, Wright–Patterson researchers spent the past three years evaluating carbon nanotube materials from NanoTechLabs, Inc., in Yadkinville, N.C., for possible use as electromagnetic protection films as well as to provide a small amount of electrical conductivity, Strong says. The Air Force has also taken a close look at "buckypaper" created by researchers at Florida State University's High-Performance Materials Institute (HPMI). Buckypaper sheets are made using densely packed single-walled carbon nanotubes.
Carbon nanotubes have specific mechanical properties that make them good candidates for the Air Force's work, says Ryne Raffaelle, director of the National Center for Photovoltaics at the U.S. Department of Energy's National Renewable Energy Laboratory. "In terms of strength-to-weight ratio, carbon nanotubes are stronger than steel but infinitely more flexible," he says.
A single carbon nanotube is typically about one nanometer in diameter (the approximate length of 10 atoms) and millions of times longer than it is wide, says Raffaelle, who previously served as director of the NanoPower Research Laboratory at the Rochester Institute of Technology (R.I.T.) in New York State, where he and his team conducted purity assessments of carbon nanotube products, including those made by Nanocomp.
Although Nanocomp and others developing new nanomaterials are on the right track, one of their main challenges will be mass-producing a product with consistent properties. This won't be easy, because each individual carbon nanotube's conductive properties are dependent on how they are formed, Raffaelle says. "It would be nice to have every tube the same," he adds, "but no one can do this."
There is a tremendous upside for success, however. Whereas it is possible to poke an ice pick through a piece of Kevlar body armor, Raffaelle says, you could not do this with a piece of fabric made from carbon nanotubes.