regeneration of thermally recycled glass fibre for cost-effective composite recycling

Insert University logosPolymer Cluster

Towards the Affordable

Recyclable Future – Low Carbon Vehicle

TARF-LCV Seminar 17-07-2014

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Regeneration of thermally recycled glass fibre for cost-effective composite recycling

Advanced Composites Group

Department of Mechanical & Aerospace Engineering

University of Strathclyde

Glasgow, Scotland

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TARF-LCV- Liu Yang (ex RA, now Lecturer)- Durai Raghavalu Thirumalai (RA)- Peter Jenkins (PhD)- Ulf Nagel (PhD)

ReCoVeR- Chih-Chuan Kao (RA)- Eduardo Sáez-Rodriguez (PhD)- Winifred Ijomah (CI)

Advanced Composite Group Recycling Team

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Insert University logosPolymer Cluster Introduction

Strathclyde Project/Posters Overview

- Fundamentals of Fibre Strength Loss

- ReCoVeRed Fibres

- Composite Performance

Conclusions

Future Work

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GlassCarbonAramid

Global Reinforcement Fibre Usage

4300

50 40KTon/year 2011

Glass Fibre is th

e most important reinforcement

in the global composites market.

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Global Glass Fibre Demand

Source OCVhttp://investor.owenscorning.com/files/doc_presentations/2014/Q1%202014%20Presentation.pdf

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Composites in AutomotiveBMW photo as shown in Modern Plastics Magazine

ELV directive 2000/53/EC ?

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Global End-of-Life Blade Material

>10 year Exponential In

crease

EU Landfill Directiv

e 99/31/EC ?

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Available End-of-Life Glass Fibre in Thermoset Composites

Assume 60% in TS

Assume we could recycle just 10% = >100KTpa business potential today

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Glass Fibres: End-of-Life Scenario4.3 MegaTons Glass Fibre

Mainly into chopped fibre thermoplastic composites.

Intrinsically recyclable

Landfill no longer acceptable – but very difficult to recover

continuous fibre

Mainly into continuous fibre

thermoset composites

ReCoVeR and reuse as valuable chopped fibre ?

Challenging to recycle - so end-of-life = landfill ? (or zero value filler)

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Thermal Processes

Incineration Fluidized bedPyrolysis Solvolysis

• Energy recovery

• Not suitable for inorganic products

• Recover organic components

• Clean fibres and length retains

Thermo-chemical processes

Mechanical grinding

• Some energy recovery from composites

• High content of inorganic material – no longer fibrous

• Not clean fibres

• Mainly reuse as very low value filler

• Clean fibres and length retains

• Energy recovery with subsequent combustion of organic products applies

GRP Recycling Techniques

Recovered Glass Fibre has very poor

performance

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Strength after Thermo-Mechanical Treatment

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The MissionEnable the development of cost-effective, drop-in, glass fibre and composite products for lightweight automotive applications based on recycled glass fibres with regenerated mechanical performance

Regenerated Composite Value Reinforcement

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Effect of Thermal Conditioning on

Glass Fibre Strength ?

• Single Fibre Strength?

• Sizing/surface changes ?

• Bulk fibre change/relaxation ?

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Strength Loss Mechanism?

J Mater Sci (2014) submitted

• Heated 15 minutes in air• Measure Strength at 23°C• Gauge length: 20 mm• Strain rate: 1.5 %/min.• 70–100 fibres per condition

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Strength Loss Mechanisms?

Untreated

HT at 400°C

AFM carried out at Univ. of Nottingham

FE-SEM carried out at AMRL Univ. of Strathclyde

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Strength Loss Mechanisms Investigation

• Fibre strength after heat (bundle vs single fibre)

• TGA of silane film degradation

• TMA for single fibre modulus and dimension changes during conditioning

• IR analysis of silane NH2 group on fibre

• XPS surface analysis of %N on fibre

• XRD for crystal growth

• AFM & SEM of fibre surface topography

• Evolution of water

Poster - Jenkins

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Current State of Strength Loss Mechanism Investigation

Mechanism of strength loss probably involves

• sizing degradation

• surface flaws (number/severity increase)

• change/relaxation in glass structure

• removal of water/dehydroxylization

More work required for full understanding

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Glass Fibres Recycled out of Composites?

• Heated Fibre vs Recycled Composite ?• Lab scale recycling of fibre out of model

composites (polyester and epoxy based)

• 1 Larger trial run on Univ. of Nottingham Fluidised Bed Reactor

• Temperature Effects?

• ReCoVeR Treatments?

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Fluidised bed process vs Lab heat treatment

Fibre characterisation•Fibre surface•Fibre strength

Material : GF-Epoxy

Bed temperature: 500°C

Residence time: 10-30 minutes

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Glass Fibres Recycled from Composites

From GF-Polyester Composite at 500°C

After additional

cleaning

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Heated vs Recycled Fibre Strengths

Posters – Kao, Yang, Durai

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HF Regenerated Fibre Strengths

Poster – Yang

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Regeneration of Glass Fibre Strength after Thermal Conditioning?

• Target strength?

• What have we achieved?• Proof of concept with HF

• ReCoVeR treatments

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Target Strength for ReCoVeRed Fibre ?

Composites Part A 32 (2001) 85-90Measured BAM 1999

Average single fibre strength from commercial chopped glass products

0.0

0.5

1.0

1.5

2.0

2.5

C E I J K L M N Z

Sin

gle

Fib

re S

tren

gth

(G

Pa)

1.5-2.0 GPaGauge length = 0.3mm !

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Target Strength for ReCoVeRed Fibre ?

10 m product for GF-PA Injection Moulding applications

Measured at BAM, Berlin

Average single fibre strength from commercial chopped glass products

1.5 GPaAt 20 mm gauge length

should be sufficient

Composites Part A 32 (2001) 85-90

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Single Fibre Strength ReCoVeRy

0.0

0.5

1.0

1.5

2.0

2.5

0H

T 1 2 3 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

Ave

. Ten

sile

Str

engt

h (

GP

a)

All APS coated 17 m Advantex with 450°C Heat Treatment

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Single Fibre Strength ReCoVeRy

• To date - 3 methods identified to regenerate single fibre strength > 1.5 GPa in glass fibres heated > 450°C

Posters – Yang, Saez, Kao, Durai

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Effect of Thermal Conditioning and ReCoVeR Treatment on Composite Performance?

• HF Proof of Concept

• Effect of GF Heat Treatment ?

• Effect of ReCoVeR?

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GF-Epoxy via vacuum infusion •CSM MAT92 manufactured by PPG Fibre Glass

•Bisphenol A Epoxy vacuum infusion grade

•RT cure 24h followed by post-curing at 60°C for 24h

Thermally conditioned glass fibre

Proof of Concept with HF for strength regeneration

Regenerate HT glass fibre

strength

Fibre strength

assessment

Fibre & composite processing

Composite performance

assessment

OK

Reactivate HT glass fibre

surface

Fibre-matrix interface

assessment

OK

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Regenerate fibre strength Reactivate fibre surface

-50%

60% recovery

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Results: Reuse regenerated glass fibre

CSM-Epoxy Composite

60% decrease50% recovery

Poster - Yang

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GF Heat Treatment & Composite Performance

Injection Moulded 30%GF-PP (1% MaPP)

ReCoVeR Target Zone

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ReCoVeR Composite Performance

Injection Moulded 30%GF-PP (1% MaPP)

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20

30

40

50

60

70

80

PP Polymer - no GF PP+GF (As Received) PP+GF (500C heattreated)

PP+GF (500C &ReCoVeR treatment)

Ten

sile

str

engt

h (

MP

a)

composite with heat treated fibre barely stronger than

polymer alone

71% composite strength ReCoVeRy

30%GF-PP

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0

10

20

30

40

50

60

PP Polymer - no GF PP+GF (As Received) PP+GF (500C heattreated)

PP+GF (500C &ReCoVeR treatment)

Un

not

ched

Ch

arp

y (k

J/m

^2)

87% impact strength ReCoVeRy

30%GF-PP

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Initial Results on ReCoVeR Fibre in PP Composites

72% ReCoVeRy of Composite Tensile Strength

87% ReCoVeRy of Unnotched Charpy Impact

• Non-optimized sizing on ReCoVeR fibres

• Higher potential ReCoVeRy performance to come

• Patent Application submitted Aug 2013

Poster - Nagel

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Insert University logosPolymer Cluster C

on

clu

sio

ns

• Development of cost-effective technology to regenerate the properties of thermally recycled glass fibres will have major environmental benefits

• Glass fibres lose most of their strength after a short heat treatment above 400ºC

• Mechanism of strength loss involves both sizing degradation and changes in glass fibre structure

• Thermal conditioning glass fibres also drastically reduces end-use composite performance

• The ACG is developing treatments to ReCoVeR the strength of thermally recycled glass fibres

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Insert University logosPolymer Cluster F

utu

re W

ork

• Good progress made on fundamentals GF strength loss but more work required for full understanding

• ReCoVeR already regenerates 50-60% of fibre strength loss – more work required to achieve 100% composite performance recovery

• Similarly, post ReCoVeR surface coating (resizing) necessary to regenerate strong fibre-matrix adhesion – similar to pristine GF products

• LCA needed

• Need to move towards pilot recycling method – to define process parameters of ReCoVeR

regeneration of thermally recycled glass fibre for cost-effective composite recycling

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