The Role of Recycled Carbon Fibres in Cost Effective ...for use in injection moulding and composites...
Transcript of The Role of Recycled Carbon Fibres in Cost Effective ...for use in injection moulding and composites...
The Role of Recycled Carbon Fibres in Cost
Effective Lightweight Structures
SPE Automotive Composites Conference & Exhibition
Novi, 2016
ELG Carbon Fibre Ltd. - Confidential 1
Overview of ELG Carbon Fibre
Established in 2011 when ELG Haniel acquired the operations of Recycled Carbon Fibre Ltd.
Patented process for recovery of carbon fibre from manufacturing waste and end-of-life products, using a modified pyrolysis process. Recovered and converted more than 1000 tonnes of carbon fibre in 2015.
R&D programmes have led to the development of recycled carbon fibre products for the compounding and composites industries.
Goal: to provide affordable, high performance materials to enable weight reduction in the transportation market.
ELG Carbon Fibre Ltd. - Confidential 2
What We Do
Carbon Fibre Reclaiming
Metal removal and cutting of large composite structures to sizes suitable for downstream processing.
Shredding of laminates and prepreg to enable efficient and consistent processing.
Fibre recovery via a modified pyrolysis process.
Carbon Fibre Conversion
Milling.
Nonwoven mat production.
Pellet production.
Product Research and Development
Aligned fibre materials.
Intermediate materials (e.g. SMC)
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ELG Carbon Fibre Ltd. - Confidential 3
Meeting The Industry’s Needs
ELG Carbon Fibre Ltd. - Confidential 3
Automotive Industry Needs
Carbon fibre at $5-$7/lb
Low cost conversion techniques to
intermediate products.
Stable supply chain.
Low carbon footprint.
Recycled Carbon Fibre Delivers
Carbon fibre at less than $5-$7/lb
Potentially low cost conversion
techniques to products suitable
for use in injection moulding and
composites manufacturing.
24,000 tonnes of carbon fibre
from manufacturing waste, much
of this coming from long term
programmes using high quality
fibres.
Less than 10% of the global
warming potential of virgin carbon
fibre.
The key challenge in delivering the potential benefits is development of usable products
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Recycled Carbon Fibre Properties
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Impregnated StrandTensile Modulus
Pre-furnace SingleFilament Tensile
Modulus
Post-furnace SingleFilament Tensile
Modulus
Ten
sile
Mo
du
lus
GP
a
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Impregnated StrandTensile Strength
Pre-furnace SingleFilament Tensile
Strength
Post-furnace SingleFilament Tensile
Strength
Ten
sile
Str
en
gth
MP
a
Difference in
test method4% reduction in
tensile strength
after pyrolysis
2% reduction in
tensile modulus
after pyrolysis
Similar mechanical properties to the original fibre
Recycled Carbon Fibre
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Challenges
Low bulk density = difficult handling
Variable fibre lengths
Variable nature of material—fibre clumps, single filaments
≠
ELG Carbon Fibre Ltd. - Confidential 6
Conversion Routes
Pellets for thermoplastic
compounding.
Nonwoven mats for
composite manufacturing.
ELG Carbon Fibre Ltd. - Confidential 6
ELG Carbon Fibre Ltd. - Confidential 7
Pellets
Designed for use in reinforcing thermoplastic compounds.
Intended as a low weight replacement for glass fibres or a low cost replacement for virgin carbon fibres.
Challenges:
Achieving sufficient fibre length to provide the same mechanical properties as 6mm chopped virgin carbon fibre.
Achieving a sufficiently high fibre loading to make the product viable as a base for further compounding.
Ensuring a dust-free product.
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Manufacturing Routes
100% carbon fibre.6mm fibre length.
Not dust free.Multiple processing steps.Lack of consistency.Energy intensive.
Diced Fibreboard
High carbon fibre content.
Not dust free unless large amounts of binder are used.Multiple processing steps—fibre damage.Lack of consistency.Energy intensive—drying.
Ring Die Pellet Mill
Dust free.Polymer compatibility ensured.Low number of processing steps.
Limitations of carbon fibre content.Feeding of recycled carbon fibres.
Extrusion
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Fibre Length
Critical fibre length dependent on the shear strength of the fibre/resin interface.
Once targets has been established based on testing, these were verified by comparing mechanical properties with compounds made using 6mm chopped virgin carbon fibre.
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Tensile Strength Comparison
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0% 5% 10% 15% 20% 25% 30% 35%
Ten
sile
Str
engt
h -
MP
a
Reinforcement Content
Tensile Strength of PP
Milled carbon 6mm chopped virgin tow Extruded pellet
Recycled carbon fibre products provide at least the same performance as virgin carbon fibre products
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Influence of Processing Parameters
Processing parameters for compounding and injection moulding being investigated in a project being carried out with the University of Warwick.
Investigating the effects of changing processing parameters on mechanical properties and fibre length.
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Influence of Processing Parameters
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0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5
Qu
an
tity
of
Fib
res
(%)
Fibre Length
Extruded RCF Pellet Pressed RCF Pellet Part From Extruded RCF Pellet
Mean fibre length in pellet 0.67mm6.4% of fibres longer than 1.5mm
Mean fibre length in part 0.48mm2.6% of fibres longer than 1.5mm
Significantly shorter fibre length in pressed fibre pellets
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Mechanical Properties of rCF Compounds
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0% 5% 10% 15% 20% 25% 30% 35%
Flex
ura
l Str
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gth
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a
Reinforcement Content
Flexural Strength of PA66
Glass Recycled Carbon Virgin Carbon
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0% 5% 10% 15% 20% 25% 30% 35%
Ten
sile
Mo
du
lus
GP
a
Reinforcement Content
Tensile Modulus of PA66
Glass Recycled Carbon Virgin Carbon
Recycled carbon fibres give the same mechanical property enhancement as virgin carbon fibres.
10% loading of recycled carbon fibre provides the same mechanical properties as 30% loading of glass fibres.
23% density reduction.
4% material cost increase.
30% to 45% loadings of recycled carbon fibre provide mechanical properties comparable to magnesium castings and aluminium castings.
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Performance comparison
30% glass fibre reinforced PA6656.9g
10% rCF reinforced PA6648.7g
15% weight reduction
Higher mechanical properties
15% weight reduction can be achieved whilst providing the same mechanical performance without any
change to the design. Higher weight savings achievable with product optimization.
Part cost increase to achieve this weight saving ~2%.
Over 750,000 tonnes of 30% glass reinforced PA66 compounds used for air inlet manifolds and cam covers
each year by the automotive industry—potential for over 110,000 tonnes of low cost weight saving!
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Recycled Carbon Fibre in Composites
Nonwoven mats are the basis of the products for composites manufacturing.
These can be either 100% carbon fibre or blends of carbon fibre with thermoplastic fibres.
Carbon fibre products can be used in liquid, prepreg and SMC applications.
Hybrid products can be used in compression mouldingapplications.
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Influence of Processing Parameters
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0.0
1.0
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3.0
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5.0
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0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0
Co
nso
lid
ati
on
Pre
ssu
re (b
ar)
Fibre Volume Fraction %
Processing Characteristics-Fibre Volume Fraction
Resin Infusion
Autoclave Prepreg
RTM/LCM and Compression moulded prepreg/SMC
Carbon fibre nonwovens have different processing characteristics and mechanical properties compared to conventional composite materials.
With proper design, they can be used to manufacture low cost, lightweight structures using most high volume manufacturing processes.
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Affordability
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Fibre cost $5-$7/lb.
Reinforcement products cost $8-$12/lb.
Weight savings depend on design
criteria, but typically the weight of a
recycled carbon fibre part is within 5%-
10% of the weight of a virgin carbon fibre
part.
Hybrid designs comprising approximately
10% virgin carbon fibre and 90%
recycled carbon fibre, typically show no
weight disadvantage but have a
significantly lower cost.
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Virgin Fibre Recycled Fibre
Fib
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ost
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g
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Virgin Fibre Fabric Recycled Fibre Fabric
Fab
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ost
€/k
g
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Mechanical Properties of Nonwovens
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Fibre volume fraction typically in the range of 27% to 40% for compression mouldingprocesses.
Properties dependent on type of feedstock, structure of the nonwoven mat and processing conditions.
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Ten
sile
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engt
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Pa
Fibre Volume Fraction
Tensile Strength
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Ten
sile
Mo
du
lus
GP
a
Fibre Volume Fraction
Tensile Modulus
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Case Study—iStream Carbon
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• Conventional stamped steel chassis: Typically hundreds of stamped metalpanels.
• iStream hybrid structural composite chassis: Simple, low cost steel tubular members.14 composite panels.
iStream photos and information courtesy of Gordon Murray Design Ltd.
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Environmental Benefits
ELG Carbon Fibre Ltd. - Confidential 20
The use of recycled carbon fibre
significantly reduces the global
warming footprint and improved the
life cycle analysis for lightweight
structures.
Global warming potential comparison prepared by Fraunhofer UMSICHT based on ELG CF 2014 operational data. Further
36% reduction in energy consumption per kg achieved in 2015.
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Summary
Carbon fibre recycling has been established at an industrial scale.
Products for the plastics compounding and composites industries offer the potential for cost effective weight saving in the automotive industry.
The use of recycled carbon fibre products also offers significant environmental benefits and an improved life cycle analysis where carbon fibre structures and components are used.
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