Environmental implications of composites

1. Environmental implications of composites John Summerscales

2. Outline of lecture raw materials production fitness for purpose end-of-use

3. Consumption of materials 1: http://dx.doi.org/10.1016/j.progpolymsci.2013.05.006 2: http://dx.doi.org/10.1016/j.eurpolymj.2013.07.025

4. Mtonnes of composites in USA

5. Raw materials • Thermoplastics, resins,carbon fibre, aramid fibres • primary feedstock = oil • potential for coal as feedstock • bio-based feedstocks • e.g. carbon fibres from rayon (cellulose) • Glass (or basalt) fibres • primary feedstock = minerals

6. Production of materials • carbon fibres pyrolysed at 1000-3000°C* • higher temperatures for higher modulus • greenhouse gases produced • aramid fibres spun from conc.H2SO4 solution • strong acid required to keep aramid in solution • glass fibres spun from “melt” at ~1375°C • greenhouse gases produced http://www.answers.com/topic/carbon-fiber http://www.answers.com/topic/kevlar http://www.answers.com/topic/fiberglass

7. Component manufacture • Net-shape production? • knitted preforms • closed mould to avoid “overspray” or equivalent • dry fibres and wet resin (infusion vs prepreg) • for aerospace prepreg manufactureup to ~40% of material from roll may go to wastebecause fragment size and orientation not useful • resin film infusion uses unreinforced resinso orientation is not an issueand % usage only limited by labour costs

8. Fitness for purpose • does lightweight structure reduce fuel consumption? • what is the normal product lifetime? • can it be designed for extended life/ re-use etc • do safety factorsunnecessarily increase materials usage?

9. End of life: hierarchy of options: • first re-use • consider re-use (or dis-assembly or recycling) at the design state • re-cycle • potential for comminuted waste as filler • Decomposition • pyrolysis/hydrolysis etc • for materials recovery, e.g. Milled Carbon Ltd. • future: enzymes, ionic liquids, sub- and super-critical processes • incineration • with energy recovery • finallylandfill • only if all else fails.

10. Plastic Resin Identification Codes PET: poly ethylene terephthalate HDPE: high density polyethylene PVC: poly vinyl chloride LDPE: low density polyethylene PP: poly propylene PS: polystyrene other: polycarbonate, ABS, nylon, acrylic or composite, etc

11. Plastic Resin Identification Codes PA6 GF30/M20 FR: • polyamide-6(caprolactam-based nylon) • 30% glass fibre • 20% mineral filler • flame retardant

12. An alternative is composting for bio-based materials • composting: biodegradation of polymers under controlled composting conditions • determined using standard methods including ASTM D 5338 or ISO 14852 • aerobic(with air present): • in open air windrows or in enclosed vessels • anaerobic(without air): • animal by-products or catering wastes • biogas is ~60-65% CH4 + 35% CO2 + others • 100 year GWP of methane = 23x that for CO2* * according to the Stern Review “The Economics of Climate Change” (2006), but the short term effect is even greater.

13. Digestion vs Composting BG Hermann, L Debeer, B de Wilde, K Blok and MK Patel,To compost or not to compost: carbon and energy footprints of biodegradable materials’ waste treatment, Polymer Degradation and Stability, June 2011, 96(6), 1159-1171.

14. Political drivers (EC) • End of Life Vehicles (ELV) Directive (2000/53/EC) • last owners must be able to deliver their vehicleto an Authorised Treatment Facilityfree of charge from 2007 • sets recovery and recycling targets • restricts the use of certain heavy metals in new vehicles • Waste Electrical and Electronic Equipment (WEEE) Directive (2002/96/EC)

15. ELV targets • end of life vehicles generate 8-9 Mtonnes of waste/year in the European Community • 2006: • 85% re-use and recovery • 15% landfill • 2015: • 95% re-use and recovery • 5% landfill

16. ELV targets • ELV targets were set to minimise landfill • total lifetime costs may be increased • e.g. for composites: • thermoset manufactured at use temperature • but recycling is difficult • thermoplastic processed at use + ~200°C • could be recycled by granulating/injection moulding for lower grade use • but higher GreenHouse Gases (GHG) early in life?

17. Carbon fibres: incineration • carbon fibres should burn to CO2in the presence of adequate oxygen(with recovery of embedded energy) • incomplete combustion may lead to surface removal and reduce diameter • rescue services concerned by health riskof inhalable fibres released fromburning carbon composite transport structures

18. Life Cycle Assessment ISO14040 series standards • The goal & scope definition • Life Cycle Inventory analysis (LCI) • Life Cycle Impact Assessment (LCIA) • Life Cycle Interpretation

19. Environmental ImpactClassification Factors:

20. Problem? Issue? No impact? Environmental Impact for Glass fibre production:

21. Recommended further reading • Y Leterrier, Life Cycle Engineering of Composites, Comprehensive Composite Materials Volume 2, Elsevier, 2000, 1073-1102. • W McDonough and M BraungartCradle to cradle: remaking the way we make things,North Point Press, New York, 2002. • SJ Pickering, Recycling technologies for thermoset composite materials: current status, Composites Part A, 2006, 37(8), 1206-1215.