Fuel-efficient fighter planes, space shuttles a step closer

Extremely thin but very strong boron nitride nanotubes can help build lighter, fuel-efficient fighter planes and space shuttles, according to a new study.
The study is the first to determine the interface strength between boron nitride nanotubes (BNNTs) and epoxy and other polymers.
"We think that this could be the first step in a process that changes the way we design and make materials that affect the future of travel on this planet and exploration of other worlds beyond our own," said Changhong Ke, associate professor at Binghamton University in New York.
"Those materials may be way off still, but someone needed to take the first step, and we have," said Ke.

Ke's group found that BNNTs in polymethyl metacrylate (PMMA) form much stronger interfaces than comparable carbon tubes with the same polymer. Furthermore, BNNT-epoxy interfaces are even stronger.
A stronger interface means that a larger load can be transferred from the polymer to nanotubes, a critical characteristic for superior mechanical performance of composite materials.

Future airplane wings and spacecraft hulls built of those BNNT composite materials could be lighter and more fuel efficient, while maintaining the strength needed to withstand the rigours of flight, researchers said.
Since nanotube wall thickness and diameters are measured in billionths of a metre, researchers extracted single BNNTs from a piece of epoxy and then repeated the process with PMMA inside an electron microscope.

Their conclusions were based on the amount of force needed to do the extractions.
This was the first time that BNNTs - more chemically and thermally stable than the more common carbon nanotubes (CNTs) - were in this kind of experiment.
BNNTs can shield space radiation better than CNTs, which would make them an ideal building material for spacecraft.
"They are both light and strong," Ke said of the two kinds of tubes.
"They have similar mechanical properties, but different electrical properties. Those differences help to add strength to the BNNT interfaces with the polymers," said Ke.
The research was published in the journal Applied Physics Letters.