1. Routes to Recycling or Disposal of Thermoset Composites
Steve Pickering
School of Mechanical, Materials and Manufacturing Engineering

2. Presentation Outline Need to Recycle
Problems in recycling thermoset composites
Recycling/Disposal Processes
mechanical recycling
thermal processing
Future Prospects

3. Need to Recycle Pressure from legislation EU Directives Landfill
End-of-Life Vehicles
Waste Electrical and Electronic Equipment
Construction and Demolition Waste

4. Does not measure recycling quality (environmental benefit)
Recycling Heirarchy
Prevent waste
Reuse product
Recycle material
Incineration
with material and energy recovery
with energy recovery
without recovery
Landfill
Does not measure recycling quality (environmental benefit)

5. Problems in Recycling Thermoset Composites
Technical Problems
Thermosetting polymers can’t be remoulded
Long fibres
Mixtures of materials (different compositions)
Contamination
Costs
Collection and Separation

6. Recycling Processes for Thermoset Composites
Mechanical Recycling
(comminution)
Thermal Processes
Pyrolysis/
Gasification
Powdered fillers
Fibrous products
(potential reinforcement)
Combustion with energy recovery (and material utilisation)
Fluidised bed process
Chemical products, fibres and fillers
Clean fibres and fillers with energy recovery

7. Mechanical Recycling Size reduction Coarse primary crushing
Hammer milling followed by grading to give:
Powder
Coarser fractions (reinforcement rich)
All scrap material is contained in recyclate (incl. different polymers, contamination, paint….)

8. Mechanical Recycling Recycling into new composites
Powdered recyclate useful as a filler
(up to 25% incorporated in new composite)
Coarser recyclate has reinforcement properties
(up to 50% substitution of glass fibre)
Several companies have been founded to commercialise recycling – ERCOM (Germany), Phoenix Fiberglass (Canada)

9. Mechanical Recycling Recycling into other products
Compounding with thermoplastics
Production of reinforcement with recyclate core to allow resin flow during impregnation
Using recyclate to provide damping (noise insulation)
Alternative to wood fibre
Asphalt

10. Thermal Processing Combustion with Energy and Material Recovery
Calorific value of thermosetting resins ~ 30 MJ/kg
Co-combustion with municipal waste in mass burn incinerators
Co-combustion in cement kilns
Co-combustion with coal in fluidised bed

11. Thermal Processing Combustion with energy recovery
Calorific value depends on inorganic content
( MJ/kg)
Filler effects:
CaCO MJ/kg
(+800 C)
ATH 1.0 MJ/kg
‘Cleaner than coal’
Bulky ash remaining

12. Thermal Processing Combustion with energy and material recovery
Cement manufacture
energy recovery from polymer
glass and fillers combine
usefully with cement minerals
fuel substitution limited to <10%
by boron in E-glass
Potential savings <£20/tonne of GRP used

13. Thermal Processing Combustion with energy and material recovery
Fluidised Bed Coal Combustion
(Limestone filled composites)
energy recovery from polymer
limestone filler absorbs oxides of sulphur from coal
commercial trial undertaken

14. Thermal Processing – Fluidised Bed Process
Cyclone
Air Inlet
Electric Pre-heaters
Fibre
Scrap CFRP
Recovered
Fluidised
Bed
Air distributor
plate
300 mm
Afterburner
Clean flue gas
To energy recovery
Fan

15. Fluidised Bed Processing
Materials and Energy Recovery
Fluidised
Bed
Scrap
FRP
Separation
of fibres
and fillers
Recovered
Fibres
Fillers
Heat
Recovery
Energy
Clean Flue Gas
Secondary
Combustion
Chamber
Fibres and fillers carried in gas flow

16. Fluidised Bed Operation
Temperature: 450 to 550 deg C
Fluidising air velocity: up to 1.3 m/s
Fluidising medium: silica sand 1mm
Able to process contaminated and mixed composites
eg: double skinned, foam cored, painted automotive components with metal inserts

17. Recovered Glass Fibres
Properties
Strength: reduced by 50% (at 450 C)
Stiffness: unchanged
Purity: 80%
Fibre length: 3 to 5 mm (wt)

18. Reuse of Recycled Glass Fibre Moulding Compounds
Moulding - virgin glass fibre
Moulding Compounds
Only effect is 25% reduction in impact strength
no change to processing conditions
demonstrator components produced
Moulding - 50% recycled glass fibre

19. Outline Process Economics Glass Fibre Recycling
Commercial Plant Schematic (5000 tonnes/year)

20. Outline Process Economics Glass Fibre Recycling
5,000 tons/year Capital £3.75million
Annual costs: £1.6 million
Annual Income: £1.3 million
Breakeven throughput: 10,000 tons/year

21. Fluidised Bed Process Clean flue gas Scrap CFRP Cyclone Afterburner
Air Inlet
Electric Pre-heaters
Fibre
Scrap CFRP
Recovered
Fluidised
Bed
Air distributor
plate
300 mm
Afterburner
Clean flue gas
To energy recovery
Fan

22. Carbon Fibre Properties
Tensile strength reduced by 25%
Little change in modulus
No oxidation of carbon fibres

23. Carbon Fibre Properties Fibre Quality
Fibre surface quality similar to virgin fibre
Clean fibres produced
~200mm
100mm
100m

24. Recovered Fibre Composite
Fibres made into polycarbonate composite
Strength
Stiffness

25. Thermal Processing Reactor Pyrolysis Process Condenser Scrap feed
Hot gases
Solid and Liquid Hydrocarbon Products
Combustible Gases to heat reactor
Solid Products (fibres, fillers, char)
Pyrolysis Process

26. Thermal Processing Pyrolysis Processes
Heating composite (400 – 800°C) in absence of air to give
hydrocarbon products – gases and liquids
fibres
Some char contamination on fibres
Hydrocarbon products potential for use as fuels or chemical feedstock
Low temperature (200°C) catalytic pyrolysis for carbon fibre
Gasification – limited oxygen – no char, fuel gases evolved

27. Thermal Processing Products from Pyrolysis (450°C)
Polyester Composite (30% glass fibre, 7% filler, 63% UP resin)
6% Gases: CO2 & CO (75%) + H2, CH4 …….
40% Oils hydrocarbons, styrene (26%)…….
15% Waxes phthalic anhydride (96%)…..
39% Solids glass fibre & fillers (CaCO3), char (16%)

28. What is best Recycling Route??
Established hierarchy and ELV Directive favour mechanical recycling techniques – but are these the best environmentally??
Detailed Life Cycle Analysis needed to identify environmental impact
Recent project in Sweden (VAMP18) has considered best environmental and cost options for recycling a range of composites

29. Prospects for Commercial Success?
ERCOM and Phoenix – viable levels of operation not achieved
Recyclates too expensive to compete in available markets
Need to develop higher grade recyclates for more valuable markets
Legislation and avoidance of landfill are new driving forces

30. Value in Scrap Composites
Energy value of polymer £ 30/tonne
Value of polymer pyrolysis products
Maleic Anhydride, Bisphenol A £1,000/tonne
Value of filler £ 30/tonne
Value of glass fibre £1,000/tonne
Value of carbon fibre £10,000/tonne

31. New Initiative EuCIA (GPRMC) initiative
ECRC (European Composites Recycling Concept)
Scheme to fund recycling to meet EU Directives
A guarantee that composites will be recycled

32. Conclusions A range of technologies is under development
material recycling
thermal processing
Key barriers to commercial success are markets at right cost
Need for environmental analysis to identify best options
Future legislation is driving industry initiatives

33. Recycled Carbon Fibre Life Cycle Analysis
Fluidised Bed Process
Recycled Carbon Fibre Life Cycle Analysis
Energy use for recovery process is 10% of virgin fibre production
40% to 45% energy reduction observed for recovered fibre composites