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.


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)



Meeting The Industry’s Needs


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


Recycled Carbon Fibre Properties


0

50

100

150

200

250

300

Impregnated StrandTensile Modulus

Pre-furnace SingleFilament Tensile

Modulus

Post-furnace SingleFilament Tensile

Modulus

Ten

sile

Mo

du

lus

GP

a

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

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


Challenges

Low bulk density = difficult handling

Variable fibre lengths

Variable nature of material—fibre clumps, single filaments

≠


Conversion Routes

Pellets for thermoplastic

compounding.

Nonwoven mats for

composite manufacturing.



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.


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


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.


Tensile Strength Comparison

0

10

20

30

40

50

60

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


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.



0

5

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25

30

35

40

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


Mechanical Properties of rCF Compounds


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300

350

400

450

0% 5% 10% 15% 20% 25% 30% 35%

Flex

ura

l Str

en

gth

MP

a


Flexural Strength of PA66

Glass Recycled Carbon Virgin Carbon

0

5

10

15

20

25

30

0% 5% 10% 15% 20% 25% 30% 35%

Ten

sile

Mo

du

lus

GP

a


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.


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!


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.




0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

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.


Affordability


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.

0

10

20

30

40

50

60

Virgin Fibre Recycled Fibre

Fib

re C

ost

€/k

g

0

10

20

30

40

50

60

70

Virgin Fibre Fabric Recycled Fibre Fabric

Fab

ic C

ost

€/k

g


Mechanical Properties of Nonwovens


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.

0.0

50.0

100.0

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450.0

500.0

20.0% 22.0% 24.0% 26.0% 28.0% 30.0% 32.0% 34.0%

Ten

sile

Str

engt

h M

Pa

Fibre Volume Fraction

Tensile Strength

0

5

10

15

20

25

30

35

40

20.0% 22.0% 24.0% 26.0% 28.0% 30.0% 32.0% 34.0%

Ten

sile

Mo

du

lus

GP

a

Fibre Volume Fraction

Tensile Modulus


Case Study—iStream Carbon


• 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.


Environmental Benefits


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.


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.


the role of recycled carbon fibres in cost effective ...for use in injection moulding and composites...

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