JEC COMPOSITES MAGAZINE - Issue #136 - September/October 2020 - 29

Composites recycling: in search of the circular economy

Fig. 3: Oak Ridge National Laboratory's Recycling-Rapid Innovation and Commercialization Lab leveraged
a Big Area Additive Manufacturing system (a) to make this utility pole (b). The pole is made of recycled
polycarbonate waste reinforced with bamboo. Images courtesy of Oak Ridge National Laboratory, U.S.
Department of Energy.

Fig. 4: The Recycling Group of
the ACMA and IACMI is working
on a composites circular
economic model. The targeted
end-of-life product is a John
Deere agricultural spray
boom (a). A CHZ Technologies
Thermolyzer™ system (b) will
be used to recover glass and
carbon fibres from the boom
after it is shredded in a grinder.
These fibres will then be used
to produce a fibre-reinforced
thermoplastic sheet material,
which can be moulded into this
door panel part (c) for a new
John Deere vehicle.

Focus

effort to organise. "I don't think this would
be easy, but I do think it's feasible, and it would
greatly increase the chances of success for all of the
wonderful technologies being developed. It would
help the industry as a whole."
Processing composite scrap
and end-of-life products
Thermoplastic composite scrap and products:
These undergo a mechanical recycling process.
They are classified, separated, shredded or
chopped and, as needed, compounded. They

can then be reused in additive manufacturing,
compression injection moulding and other
processes.
Thermoset composite scrap and products:
These undergo a thermo-chemical recycling
process. The scrap or product is classified
and converted into a size that will fit into the
processing machinery.
Pyrolysis is the primary processing method.
During pyrolysis, the composite is heated in
the absence of oxygen. It decomposes, the

Conversion to energy: In some cases, composite fibres are not recovered but rather conumed along with the entire composite matrix
and used as a fuel stock for cement kilns. To
heat cement ingredients to temperatures of
about 1450°C, kilns consume large volumes
of fuel. Composite scrap, sometimes blended
with other waste, serves as an engineered fuel
for the kilns. Engineered fuel is an alternative
to coal and generates lower greenhouse
emissions. PVC in composites poses some
chlorine emissions risks, but some kilns are
designed to mitigate this risk.
Keeping an eye on regulations
The perceived riskiness and complexity
of composite materials and their recycling
processes influence how both are viewed from
a regulatory perspective. Wagger encouraged
ACMA Composites Recycling Conference
participants to stay tuned to ongoing debates
over plastic waste classification by the
Organisation for Economic Co-Operation
and Development (OECD). As of this writing, the OECD has not adopted an approach
to incorporating new Basel Convention (BC)
amendments for plastic waste categorisation.
The BC's intention is for nations to have greater control over the movement of plastics that

Feature Sustainability

Design for Recycling®
The Institute of Scrap Recycling Industries Inc. (ISRI) has a Design for Recycling® initiative to
encourage manufacturers to consider the destiny of their products during the design stage.
ISRI presents an annual Design for Recycling award. Products designed for recycling adhere
to the following general principles:
- Contain the maximum amount of materials that are recyclable;
- Are easily recycled through current or newly designed recycling processes and procedures;
- Are cost effective to recycle, whereby the cost to recycle does not exceed the value of
the recycled materials;
- Are free of hazardous materials that are not recyclable or impede the recycling process;
- Minimise the time and cost involved to recycle the product;
- Reduce the use of raw materials by including recycled materials and/or components;
- Have a net gain in the overall recyclability of the product while reducing the overall
negative impact on the environment.
Source: ISRI

fibre is recovered, and a fuel gas is captured
from the resins and polymers. The recovered
fibres can be cleaned and used in thermoset
composite processes. Or they can be compounded and used in thermoplastic processes.
At the ACMA conference, several presentations highlighted the Thermolyzer™ by
CHZ Technologies. A pyrolysis system, the
Thermolyzer generates gases while decomposing composites. These pass through a
battery of aqueous scrubbers to separate toxic
materials. Most of the gas is used as a sustainable power source for the Thermolyzer. CHZ
partner Chuck Ludwig said the company has
been working with IACMI and other industry
partners to identify the processing "sweet
spot" for composite materials so that the
recovered fibres retain optimal performance
characteristics. For example, CHZ has made
adaptations to its process to minimise the heat
and stress on delicate glass fibres. "The more
gently you can handle the fibres, the more likely
you will be to find a good application for them,"
he said.

/ jec composites magazine

N°136 September - October 2020

JEC COMPOSITES MAGAZINE - Issue #136 - September/October 2020

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #136 - September/October 2020