Bullet-proof protection may be about to get more bullet proof. A team of researchers has created a new kind of nanofiber that can extend to seven times its original length—and is tougher than kevlar, too.
Scientists at UT Dallas have created a new kind of fiber which makes use of its electromechanical properties to absorb energy. While Kevlar can absorb up to 80 joules per gram before it breaks, the new material can handle up to 98 joules per gram. That could make it extremely useful in applications like military vehicles and body armor.
The team took inspiration from the piezoelectric action—where pressure is converted into electrical charges—observed in collagen fibers within human bone. The researchers recreated the collagan fibers by spinning polyvinylidene fluoride (PVDF) and polyvinvylidene fluoride trifluoroethylene (PVDF-TrFE)—themselves piezoelectric materials—into nanofibers. They then twisted these strands into yarns.
When stretched, these polymer-based yarns create an electrical charge which acts to attracts the polymer strands back in on themselves—an attraction found to be 10 times stronger than a hydrogen bond. (Hydrogen bonds, by the way, are considered some of the strongest inter-molecular forces we know of.) The result is a material that can absorbs terrific amount of energy before it fails. The result are published in ACS Applied Materials and Interfaces.
Currently, the nanofibers are very small, so the next step for the researchers is to work out how to produce and use the material in bulk. If they can, the armor of the future may be made from little more than simple twisted yarn—one that just happens to be ultra-tough.