Tech Briefs Magazine - February 2022 - 26

Materials & Coatings
Healable Carbon Fiber Composite
The carbon fiber reinforced material can be repeatedly healed with heat.
University of Washington, Seattle, WA
B
ecause of their high strength and
light weight, carbon-fiber-based composite
materials are gradually replacing
metals for advancing all kinds of products
and applications, from airplanes to wind
turbines to golf clubs. But once damaged
or compromised, the most commonly
used carbon fiber materials are nearly
impossible to repair or recycle.
A team of researchers has created a
new type of carbon fiber reinforced material
that is as strong and light as traditionally
used ones but can be repeatedly
healed with heat, reversing any fatigue
damage and providing a way to break it
down and recycle it when it reaches the
end of its life. Either traditional heat
sources or radio frequency heating can
be used to reverse and postpone its aging
process indefinitely.
The material is part of a recently de -
veloped group known as carbon fiber
reinforced vitrimers (CFRP). The materials
typically used today, whether in sporting
goods or aerospace, are carbon fiber
reinforced polymers (CFRP). Tra ditional
CFRPs typically fall into two categories:
thermoset or thermoplastic. The " set " variety
contains an epoxy, a glue-like material
where the chemical links holding it together
harden permanently. The " plastic " version
contains a softer type of glue, so it can
be melted back down and reworked, but
this becomes a drawback for high strength
and stiffness. Vitrimers on the other hand,
can link, unlink, and re-link, providing a
middle ground between the two.
A sample of a healable carbon fiber composite material being studied. (Photo: Andy Freeberg/
University of Washington)
If each of these materials was a room
full of people, in the thermoset room, all
of the people are holding hands and
won't let go. In the thermoplastic room,
people are shaking hands and moving
around. In the vitrimer room, people
shake hands with their neighbor but
have the capacity to exchange handshakes
and make new neighbors so that
the total number of interconnections
remains the same. That re-connection is
how the material gets repaired.
The team believes vitrimers could be a
viable alternative for many products currently
manufactured from thermosets,
something badly needed as thermoset
composites have begun piling up in
landfills. Healable CFRPs would be a
major shift toward a dynamic material
with a different set of considerations in
terms of lifecycle cost, reliability, safety,
and maintenance.
For more information, contact Andy
Freeberg at afree@uw.edu; 206-221-1952.
Dyeing Process Gives Textiles Electronic Properties
Textiles and items of clothing can be converted into e-textiles without affecting their
original properties.
Saarland University, Saarbrücken, Germany
W
hether in the fitness sector, in
medicine, or in the entertainment
industry, IT devices worn on the body,
such as smartwatches, are becoming in -
creasingly popular. Applications of this
kind benefit when the input device
adapts to the body as naturally as possible;
for example, in the form of electrosensitive
substances called e-textiles.
Researchers developed a method to pro26
Cov
duce
these textiles in a comparatively
uncomplicated manner to open up new
usage scenarios.
The method integrates interactive
functions directly into the fibers of textiles
instead of just attaching electronic
components to them. Previous approaches
to the production of these textiles are
complex and influence the wearing comfort
of the material. The new method
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allows textiles and items of clothing to be
subsequently converted into e-textiles
without affecting their original wearing
properties - they remain thin, elastic,
and supple. This enables them to experiment
quickly and in a variety of ways with
new forms of e-textiles and to integrate
them into IT devices.
Especially for devices worn on the
body, it is important that they restrict
Tech Briefs, February 2022

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Tech Briefs Magazine - February 2022

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