Metal-rubber composite
Researchers have developed a fiber that combines the elasticity of rubber with
the strength of a metal.
The resulting composite is a sturdier material that can be incorporated into
lightweight robotics, packaging materials, next generation textiles and even
in biomedical applications.
"A good way to explain the material is to think of elastics and metal wires.An
elastic can stretch a lot, but it does not take much force to stretch it.A
metal wire requires a lot of force to be stretched, but it does not take much
"Our fibers have the best of these two worlds," explained Professor Michael
Dickey, of the State University of North Carolina, USA.
The fibers consist of a metal core of gallium encased by an elastic polymer
coating.
When placed under stress, the fiber has the strength of the metal core. But
when the force is too much and the metal breaks, the fiber does not break -
the polymer coating absorbs the tension between the broken metal parts and
transfers the voltage back to the still intact parts of the metal core.
"Every time the metal core breaks, it dissipates energy, allowing the fiber to
continue to absorb energy as it stretches," explained Dickey. "Instead of
splitting in two when stretched, it can stretch up to seven times the original
length before breaking, which happens while many additional breaks in the yarn
are generated along the way."
Tenacity of the skin
The fiber response is similar to the way human connective tissue is maintained
when a bone breaks.
"There is a lot of interest in engineering materials to mimic the tenacity of
the skin - and we have developed a fiber that has overcome the tenacity of the
skin and is still elastic like the skin," said Dickey.
The fibers can be reused by melting the metal cores again - gallium fuses at a
mere 30 ° C, which means that the polymer is not affected.
"This is just a proof of concept, but it has a lot of potential. We are
interested to see how these fibers could be used in light robotics or when
woven into fabrics for various applications," said Dickey.
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Bibliography: Toughening stretchable fibers via serial metal fracturing Christopher B. Cooper, Ishan D. Joshipura, Dishit P. Parekh, Justin Norkett, Russell Mailen, Victoria M. Miller, Jan Genzer, Michael D. Dickey Science Advances Vol .: 5, no. 2, eaat4600 DOI: 10.1126 / sciadv.aat4600 |
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Materials