SAMPE Journal - January/February 2023 - 68

MARKET OVERVIEW / SUSTAINABILITY
Growing a Technical Community
for Sustainability
Why Recycling?
Polymer composites are widely employed in various
industries, including aerospace, automotive, marine,
and renewable energy sectors. While composite
materials are often designed to be durable and
sustainable, with strong mechanical properties and
long lifespan, their end of life still represents a grand
challenge: How to recycle and enable their extended
use? Just like many other materials, waste management
solutions of composite products are needed to allow
their minimum impact on the environment, ensuring
no leaking of harmful products to cause damage.
Furthermore, the recovery and reuse of high value
components from composites waste can reduce the
manufacturing cost, while also lowering the carbon
emission and energy consumption as the conventional
composite processing is often energy intensive. To
provide an example, production of carbon fibers
(CF) consumes a significantly high amount of energy,
in the range of 200-600 MJ/kg. With the ability to
recover waste materials, CFs recycling would require
energy consumption of 30-50 MJ/kg, suggesting a
potential of 80-90% of the total energy reduction
compared to manufacturing virgin CFs. Additionally,
many government policies and initiatives have
been established to promote, or even mandate the
use of waste as a resource/feedstock. Collectively,
composite recycling now becomes an integral part
of global efforts of transforming the entire industry
from linear to circular economy, ultimately achieving a
carbon neutral society.
Composite Recycling Streams and Methods
For composite recycling, each segment involves an
operation chain, which is deeply interconnected with
the rest. As shown in Figure 1, the feedstock of waste
composites is typically from post-consumer products
after reaching their end life, no longer repairable or
useful. Following collections and transportation, these
materials will enter the waste stream for recycling,
which is the core step in the system for waste
68 | SAMPE JOURNAL | JANUARY FEBRUARY 2023
management. Briefly, two recycling methods exist.
First, mechanical recycling involves reprocessing
waste materials into new products, maintaining a
constant chemical identity during the entire process.
Alternatively, chemical recycling can convert waste into
new components, such as monomers, fuels, carbons,
and other functional products. Mechanical recycling
is typically preferred for single-stream thermoplastic
waste, while chemical recycling is desired for waste
materials that are non-processable (e.g. thermosets).
It is important to note that composites are inherently
heterogeneous, containing multiple components of
reinforcing agents, polymer matrices, and binders;
this characteristic feature makes their recycling
becomes an interactable challenge. As an example,
while pyrolysis of composites at high temperatures
can create fuels from polymer matrix decomposition,
this process leads to downgraded filler properties due
to high temperature processing. It is now recognized
that separating different components within the
waste composite stream are important for enabling
their efficient recycling in sequential steps. Finally,
needs, prices, and quality requirements of recycled
or recovered products are also crucial factors to drive
the market of composite recycling.
Who Are We? - Recycling of Composites Technical
Committee
The mission of the Recycling of Composites TC is to
be a melting pot/composite of industry professionals,
academics, and government officials that will support
the: 1) maturation and standardization of R4
re-purpose)
(i.e.
reclamation,
recycle,
reuse,
material
quality and life cycle assessment, 2) continuous
development and transfer of fundamental knowledge,
3) adoption of an effective mentorship program for
young professionals, and 4) engagement with the
general public regarding sustainability.
Our vision is to be the main forum/hub for the
composites industry to drive innovation in the realm
of sustainability and recycling for the next generation.
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SAMPE Journal - January/February 2023

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