JEC COMPOSITES MAGAZINE - Issue #146 - June/July 2022 - 93

How and where we found reclaimed Carbon Fibre for Additive Manufacturing technologies
Focus
Consortium: Warrant Group (coordinator), NTUA (technical coordinator),
Ghent University, Eurecat, ITENE, Leitat, IRT Jules Verne, Sigmatex,
Adamant Composites, Cambridge Nanomaterials Technology,
Techedge, Dalbello, Centexbel, Maier, Biog3D, IRES, Jotis, Lavrion
Technological and Cultural Park.
Fig. 2: a: Photograph of 6 mm recycled CF prepreg after supercritical CO2
tion; b: corresponding SEM image
extracfi
bres. End-of-spool was therefore selected for Repair3D (3k for
CFAM and 24k for CFIP).
For FFF and DPAM
For these technologies, a compound must be prepared in order to
be used directly, or for fi lament preparation. Th is requires adding CF
in a controlled way to the compounder. Several fi bres were tested:
- use of a chopper (Chopcot® T6) for textile wastes:
- for end-of-spool: size control (OK)
- or pancake: no compatible due to unwind issue (NOK)
- aft er cryogenic milling of textile to reduce the size: too fl uff y
(NOK)
- aft er supercritical water solvolysis from cured composite: too
fl uff y and with no size control (NOK)
- aft er supercritical CO2
preliminary cutt ing step (OK).
Supercritical CO2
extraction from uncured prepreg with a
is used as " green solvent " to extract a fraction of
the prepreg matrix from the chopped prepregs. Th is process stopped
the polymerisation reaction due to a partial extraction of bisphenol-A/F
and aminophenol from epoxy resin. As consequence,
the fi bres are neither fl uff y nor tacky, they become quite simple to
process. By previously cutt ing uncured prepreg (with Zünd equipment),
it is easy to control the size and get ready to use reclaimed CF
(rCF) at the end of the recycling process (Figure 2). In Repair3D, 6
mm was chosen as standard length for compound preparation. Such
rCF, aft er extraction, was processed with polyamide 12, copolyester
and thermoplastic polyurethane matrix.
Sustainability dimension
Th e environmental and economic features of this novel procedure
(supercritical CO2
extraction applied for uncured prepreg) indicate
that it is an att ractive and promising technology in terms of
reduced GHG emissions and cost impacts. Techno-economic estimation
values for a plant that could process ~145 tons/year would
result in producing 6 mm rCF with the same order of magnitude in
CO2
-equivalent emissions and cost-per-kg as commercial recycling
alternatives. Utilisation of the organic by-product, and potential use
as monomers in polymers, would increase the environmental and
economic sustainability of the technology. Valorisation of uncured
prepreg, a current waste stream in composite manufacture that is
diffi cult to recycle, would have a twofold advantage. On one hand,
it would minimise the composite waste going to landfi ll, and on the
other hand, create added-value products through secondary raw materials
with similar intrinsic properties than virgin [2].
Focus
IRT Jules Verne is an industrial research centre located near Nantes
in western France dedicated to manufacturing. Its vocation is to
improve the competitiveness of strategic industrial sectors in France
by creating disruptive technologies for manufacturing processes,
with the goal of speeding up innovation and technology transfer to
factories. One of our missions in Repair3D is to determine what type
of recycled carbon fi bres can be processed by AM technologies.
For APF
Considering CF powder, two options are evaluated: cryogenic milling
for textile wastes and direct use of milled powder from the Airbus
Nantes plant.
Cryogenic milling was tested for textile wastes, cured prepregs. Th is
technique is indeed useful for gett ing milled CF, but for textiles,
as mentioned, CF are too fl uff y to be processable. Several types of
wastes can be processed using this technique and are useful for obtaining
milled CF. Th e best results are obtained with cured prepregs.
Th e second option is to directly use the milled CF produced during
fi nishing operations in the Airbus Nantes plant. Compare with the
option involving cured prepreg/cryogenic milling and milled waste,
these two powders contain epoxy. Th e choice was therefore made to
use Airbus Nantes plant waste for APF technology.
A smart choice to make the most of carbon waste
From the panel of diff erent wastes studied in Repair3D project, we were
able to select the best options, and process the fi bres to obtain products
usable in AM processes. Th ese rCF incorporated in semi-products have
been used to produce various demonstrators, as a proof of concept for
future manufacturing sectors such as automotive (undergoing work),
sport, health, and so on. End-of-spool wastes have been used in CFAM
technology to produce personalised orthopaedic assistive devices, UDprepreg
CF were integrated in fi laments used in FFF technology, and
make 3D-printed ski-boots, and milled CF used to print wearable electronics
devices using APF.
More information:
www.irt-jules-verne.fr/en/
www.repair3d.net
References
[1] Guriec HP, Martin S, Moisan S, Novel Method for Unpolymerized
Prepreg Recycling Using Supercritical CO2
Extraction, ECCM 2022
[2] Gkika A, Petrakli F, Vlysidis A, Karagiannis P, Moisan S, Koumoulos
E, Life Cycle Assessment and Life Cycle Costing on recycled post-industrial
composite waste, ECCM 2022
N°146 June - July 2022 / jec composites magazine
93
http://www.irt-jules-verne.fr/en/ http://www.repair3d.net
JEC COMPOSITES MAGAZINE - Issue #146 - June/July 2022

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