1. Regeneration of thermally recycled glass fibre for cost-effective composite recycling
Advanced Composites Group
Department of Mechanical & Aerospace Engineering
University of Strathclyde
Glasgow, Scotland

2. Advanced Composite Group Recycling Team
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)

3. Strathclyde Project/Posters Overview
Introduction
Strathclyde Project/Posters Overview
Fundamentals of Fibre Strength Loss
ReCoVeRed Fibres
Composite Performance
Conclusions
Future Work

4. Global Reinforcement Fibre Usage50 40
KTon/year 2011
Glass Fibre is the most important reinforcement in the global composites market.
4300 4

5. Global Glass Fibre Demand
Source OCV

6. Composites in Automotive BMW photo as shown in Modern Plastics Magazine
ELV directive 2000/53/EC ? 6

7. Global End-of-Life Blade Material
>10 year Exponential Increase
EU Landfill Directive 99/31/EC ?

8. Available End-of-Life Glass Fibre in Thermoset Composites
Assume we could recycle just 10% = >100KTpa business potential today
Assume 60% in TS

9. Glass Fibres: End-of-Life Scenario
4.3 MegaTons Glass Fibre
Mainly into chopped fibre thermoplastic composites. Intrinsically recyclable
ReCoVeR and reuse as valuable chopped fibre ?
Mainly into continuous fibre thermoset composites
Landfill no longer acceptable – but very difficult to recover continuous fibre
Challenging to recycle - so end-of-life = landfill ?
(or zero value filler) 9

10. GRP Recycling Techniques
Mechanical grinding
Thermal Processes
Thermo-chemical processes
Incineration
Pyrolysis
Fluidized bed
Solvolysis
Recovered Glass Fibre has very poor performance
Not clean fibres
Mainly reuse as very low value filler
Some energy recovery from composites
High content of inorganic material – no longer fibrous
Energy recovery
Not suitable for inorganic products
Clean fibres and length retains
Energy recovery with subsequent combustion of organic products applies
Recover organic components
Clean fibres and length retains

11. Strength after Thermo-Mechanical Treatment

12. The Mission The Research Goals
Regenerated Composite Value Reinforcement
The Mission
Enable 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
Generate fundamental understanding of the changes in glass fibres caused by thermo-mechanical conditioning ( °C)
Develop cost effective treatments to regenerate the performance of thermo-mechanically treated glass fibres
Produce examples of glass fibre and composite products using regenerated glass fibres
The Research Goals

13. Effect of Thermal Conditioning on
Glass Fibre Strength ?
Single Fibre Strength?
Sizing/surface changes ?
Bulk fibre change/relaxation ?

14. Strength Loss Mechanism?
Heated 15 minutes in air
Measure Strength at 23°C
Gauge length: 20 mm
Strain rate: 1.5 %/min.
70–100 fibres per condition
J Mater Sci (2014) submitted

15. Strength Loss Mechanisms?
FE-SEM carried out at AMRL
Univ. of Strathclyde
Untreated
HT at 400°C
AFM carried out at Univ. of Nottingham

16. 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

17. 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

18. 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?

19. Fluidised bed process vs Lab heat treatment
Material : GF-Epoxy
Bed temperature: 500°C
Residence time: minutes
Fibre characterisation
Fibre surface
Fibre strength

20. Glass Fibres Recycled from Composites
From GF-Polyester Composite at 500°C
After additional cleaning

21. Heated vs Recycled Fibre Strengths Posters – Kao, Yang, Durai

22. HF Regenerated Fibre Strengths
Poster – Yang

23. Regeneration of Glass Fibre Strength after Thermal Conditioning?
Target strength?
What have we achieved?
Proof of concept with HF
ReCoVeR treatments

24. Target Strength for ReCoVeRed Fibre ?
Average single fibre strength from commercial chopped glass products
GPa
Gauge length = 0.3mm !
Measured BAM 1999
Composites Part A 32 (2001) 85-90

25. Target Strength for ReCoVeRed Fibre ?
Average single fibre strength from commercial chopped glass products
1.5 GPa
At 20 mm gauge length should be sufficient
10 mm product for GF-PA Injection Moulding applications
Measured at BAM, Berlin
Composites Part A 32 (2001) 85-90

26. Single Fibre Strength ReCoVeRy
All APS coated 17 mm Advantex
with 450°C Heat Treatment

27. Single Fibre Strength ReCoVeRy Posters – Yang, Saez, Kao, Durai
To date - 3 methods identified to regenerate single fibre strength > 1.5 GPa in glass fibres heated > 450°C
Posters – Yang, Saez, Kao, Durai

28. Effect of Thermal Conditioning and ReCoVeR Treatment on Composite Performance?
HF Proof of Concept
Effect of GF Heat Treatment ?
Effect of ReCoVeR?

29. Proof of Concept with HF for strength regeneration
Reactivate HT glass fibre surface
Fibre-matrix interface assessment OK
Thermally conditioned glass fibre
Fibre & composite processing
Regenerate HT glass fibre strength
Fibre strength assessment OK
Composite performance assessment
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

30. Regenerate fibre strength Reactivate fibre surface
60% recovery
-50% 30

31. Results: Reuse regenerated glass fibre
CSM-Epoxy Composite
60% decrease
50% recovery
Poster - Yang 31

32. GF Heat Treatment & Composite Performance
ReCoVeR Target Zone
Injection Moulded 30%GF-PP (1% MaPP)

33. ReCoVeR Composite Performance
Injection Moulded 30%GF-PP (1% MaPP)

34. ReCoVeR Composite Performance
30%GF-PP

35. ReCoVeR Composite Performance
30%GF-PP

36. Initial Results on ReCoVeR Fibre in PP Composites
72% ReCoVeRy of Composite Tensile Strength
87% ReCoVeRy of Unnotched Charpy Impact
Poster - Nagel
Non-optimized sizing on ReCoVeR fibres
Higher potential ReCoVeRy performance to come
Patent Application submitted Aug 2013

37. 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
Conclusions 37

38. 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
Future Work 38