U.S. researchers develop new technique to produce ultra-strong, resilient nanofibers for protective armors

SAN FRANCISCO, Jan. 6 (Xinhua) -- Researchers at the Massachusetts Institute of Technology (MIT) in the United States have developed a new process that can produce ultrafine but exceptionally strong and tough nanofibers that are possibly used to manufacture protective armors, a new study says.

The research, conducted by Gregory Rutledge, MIT professor of chemical engineering, described the new process as gel electrospinning in a paper to be published in the February edition of the Journal of Materials Science.

In order to make the new-generation nanofiber, Rutledge and his team worked hard to eliminate the tradeoffs in traditional way of material science, which either sacrifices strength for toughness or vice versa.

The new process adds electrical forces to a variation of a traditional method called gel spinning, which can produce ultrafine fibers of polyethylene that match or exceed the properties of some of the strongest fiber materials, such as Kevlar and Dyneema.

Kevlar and Dyneema are top high-performance materials widely used in the production of bullet-stopping body armors or ropes for extreme conditions.

Compared to carbon fibers and ceramic fibers, the new gel-electrospun polyethylene fibers have similar degrees of strength but are much tougher with lower density, which outperform the standard materials by a wide margin, Rutledge said.

He said the new gel-electrospun fibers seem to combine the desirable qualities of strength, stiffness and toughness in ways that outperform glass fibers or steel wire.

Owing to the electrical forces added to the conventional gel spinning process, which is a single-stage process rather than the multiple stages commonly known in traditional way of production, the MIT researchers are able to get much more highly drawn fibers with diameters of a few hundred nanometers rather than the typical 15 micrometers.

Unlike the fibers drawn out in the conventional way of mechanical pulling, the electrically drawn fibers induce a "whipping" instability process that produces their ultrafine dimensions, which give the fibers unique properties that make protective materials much stronger but less bulky.

The scientists believe that level of toughness of the fibers has a promising prospect for many future applications.

The research was supported by the U.S. military and the National Science Foundation's Center for Materials Science and Engineering. Enditem