Bullet-proof protection may be about to get more bullet proof. A team of researchers has created a new kind of nanofibre 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 fibre 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 armour.
The team took inspiration from the piezoelectric action — where pressure is converted into electrical charges — in collagen fibres within human bone. The researchers recreated the collagan fibres by spinning polyvinylidene fluoride (PVDF) and polyvinvylidene fluoride trifluoroethylene (PVDF-TrFE) — themselves piezoelectric materials — into nanofibres. They then twisted these strands into yarns.
When stretched, these polymer-based yarns create an electrical charge which acts to attracts the polymer back in on itself — an attraction found to be 10 times stronger than a hydrogen bond. (Hydrogen bonds 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 nanofibres 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 armour of the future may be made from little more than simple twisted yarn — one that just happens to be ultra-tough. [ACS Applied Materials and Interfaces via PhysOrg]
Picture: Majid Minary/UT Dallas