A team of material engineers at the University of Nebraska - Lincoln have created a type of nanofiber that is both tough and strong, leading to new possibilities for a number of objects, from airplanes to body armor. The discovery is displayed this week on the cover of the April issue of the American Chemical Society's journal, ACS Nano.
"Whatever is made of composites can benefit from our nanofibers," said team leader and McBroom Professor of Mechanical and Materials Engineering and member of UNL's Nebraska Center for Materials and Nanoscience Yuris Dzenis. "Our discovery adds a new material class to the very select current family of materials with demonstrated simultaneously high strength and toughness."
Toughness refers to the amount of energy required to break an object. A rubber ball, for instance, is a tough material. Strength, on the other hand, is a material's ability to carry a load. A plate is a strong object, but not very tough. Accordingly, strength and toughness were not thought to go hand in hand.
In order to create a nanofiber that is both tough and strong, the UNL team used electrospinning to create an unusually thin polyacrilonitrile nanofiber. Electrospinning is a well-established process of creating nanofibers, whereby high voltage is applied to a polymer solution until a length of nanofiber is produced through a liquid ejection. The team created a nanofiber that was exceptionally small, called polyacrilonitrile, and found that, by making it thinner than ever before, the nanofiber became both tougher and stronger.
The find has major implications for strong and tough materials.
"If structural materials were tougher, one could make products more lightweight and still be very safe," Dzenis said.
A classic example of such a product is the bulletproof vest, which must be both tough and strong.
"To stop the bullet, you need the material to be able to absorb energy before failure, and that's what our nanofibers will do," he said.
Research for the UNL study was funded by the Air Force Office of Scientific Research, the National Science Foundation and a U.S. Army Research Office Multidisciplinary University Research Initiative grant.
