Researchers used the PVC method to produce the first high-quality BNNTs that are long enough to be spun into macroscopic yarn, in this case centimeters long. A cotton-like mass of nanotubes was finger-twisted into a yarn about one millimeter wide, indicating that the nanotubes themselves are about one millimeter long.
"They're big and fluffy, textile-like," said Kevin Jordan, a staff electrical engineer at Jefferson Lab. "This means that you can use commercial textile manufacturing and handling techniques to blend them into things like body armor and solar cells and other applications."
Transmission electron microscope images show that the nanotubes are very narrow, averaging a few microns in diameter. TEM images also revealed that the BNNTs tended to be few-walled, most commonly with two-five walls, although single-wall nanotubes were also present. Each wall is a layer of material, and fewer-walled nanotubes are the most sought after.
The researchers say the next step is to test the properties of the new boron-nitride nanotubes to determine the best potential uses for the new material. They are also attempting to improve and scale up the production process.
"Theory says these nanotubes have energy applications, medical applications and, obviously, aerospace applications," said Jordan.
Smith agreed, "Some of these things are going to be dead ends and some are going to be worth pursuing, but we won't know until we get material in people's hands."
Fibrils of boron-nitride nanotubes are formed through the pressurized vapor/condenser method. The synthesis technique was developed by researchers at NASA's Langley Research Center, the Department of Energy's Thomas Jefferson National Accelerator Facility and the National Institute of Aerospace. The nanotube fibrils are produced when the FEL laser beam strikes a target of pressed boron powder. The number indicates laser power level in arbitrary units; about 1.5 kW in actuality. The target rotates to distribute the laser heat evenly.
(Photo Credit: Source: DOE's Jefferson Lab)
A yarn spun of boron-nitride nanotubes suspends a quarter. The nanotubes in this yarn were produced with a new technique discovered by researchers at NASA's Langley Research Center, the Department of Energy's Thomas Jefferson National Accelerator Facility and the National Institute of Aerospace. The nanotubes are highly crystalline and have a small diameter. They also structurally contain few walls and are very long.
(Photo Credit: Source: DOE's Jefferson Lab)