Healable carbon fiber composite offers path to long-lasting, sustainable materials

Date:
November 4, 2021
Source:
University of Washington
Summary:
Researchers have created a new type of carbon fiber reinforced
material that is as strong and light as traditionally used
materials, but can be repeatedly healed with heat, reversing any
fatigue damage. This also provides a way to break it down and
recycle it when it reaches the end of its life.



FULL STORY ========================================================================== Because 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 there's a trade-off. Once damaged or compromised,
the most commonly-used carbon fiber materials are nearly impossible to
repair or recycle.


==========================================================================
In a paper published Nov. 2 in the journal Carbon, a team of researchers describes a new type of carbon fiber reinforced material that is as
strong and light as traditionally used materials but can be repeatedly
healed with heat, reversing any fatigue damage. This also provides a
way to break it down and recycle it when it reaches the end of its life.

"Developing fatigue-resistant composites is a major need in the
manufacturing community," said co-lead author Aniruddh Vashisth,
University of Washington assistant professor of mechanical
engineering. "In this paper, we demonstrate a material where 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 developed group known as carbon fiber reinforced vitrimers,
named after the Latin word for glass, that show a mix of solid and fluid properties. The materials typically used today, whether in sporting
goods or aerospace, are carbon fiber reinforced polymers.

Traditional carbon fiber reinforced polymers 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 relink, providing a middle ground between the two.

"Imagine each of these materials is a room full of people," Vashisth
said. "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 all around. In the vitrimer room people shake hands with their
neighbor but they have the capacity to exchange handshakes and make
new neighbors so that the total number of interconnections remains
the same. That reconnection is how the material gets repaired and this
paper was the first to use atomic-scale simulations to understand the underlying mechanisms for those chemical handshakes." The research
team believes vitrimers could be a viable alternative for many products currently manufactured from thermosets, something badly needed because thermoset composites have begun piling up in landfills. The team says
that healable vitrimers would be a major shift toward a dynamic material
with a different set of considerations in terms of life-cycle cost, reliability, safety and maintenance.

"These materials can translate the linear life cycle of plastics to a
circular one, which would be a great step toward sustainability," said co-senior author Nikhil Koratkar, professor of mechanical, aerospace
and nuclear engineering at Rensselaer Polytechnic Institute.

The research team also includes Mithil Kamble and Catalin Picu at
Rensselaer Polytechnic Institute and Hongkun Yang and Dong Wang at the
Beijing University of Chemical Technology. This research was funded by
the U.S. Army and NASA through the Vertical Lift Research Centers of
Excellence program, the National Science Foundation, the John A. Clark
and Edward T. Crossan Chair Professorship at Rensselaer Polytechnic
Institute, the University of Washington, and the company Software for
Chemistry & Materials.

========================================================================== Story Source: Materials provided by University_of_Washington. Original
written by Andy Freeberg. Note: Content may be edited for style and
length.


========================================================================== Journal Reference:
1. Mithil Kamble, Aniruddh Vashisth, Hongkun Yang, Sikharin Pranompont,
Catalin R. Picu, Dong Wang, Nikhil Koratkar. Reversing fatigue in
carbon- fiber reinforced vitrimer composites. Carbon, 2021; DOI:
10.1016/ j.carbon.2021.10.078 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/11/211104115358.htm

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