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Environmental implications of composites

Environmental implications of composites. John Summerscales. Outline of lecture. raw materials production fitness for purpose end-of-use Life Cycle Assessment (LCA). Earth Overshoot Day. the day in which we exhaust our ecological budget for the year: 19 December 1987 21 August 2010

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Environmental implications of composites

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  1. Environmental implications of composites John Summerscales

  2. Outline of lecture raw materials production fitness for purpose end-of-use Life Cycle Assessment (LCA)

  3. Earth Overshoot Day the day in which we exhaustour ecological budget for the year: 19 December 1987 21 August 2010 29 July 2019 days/earth used by human population [Mathis Wackernagel]

  4. 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

  5. Mtonnes of composites in USA

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

  7. 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

  8. 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

  9. 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?

  10. End of life: hierarchy of options: • firstre-use • consider re-use (or dis-assembly or recycling) at the design state • re-cycle • difficult to de-ply laminated composites • high Vf composites may need dilution with additional matrix material • potential for comminuted waste as filler • decomposition • pyrolysis/hydrolysis etc • for materials recovery, e.g. ELG carbon Fibre Ltd. • future: enzymes, ionic liquids, sub- and super-critical processes • incineration • with energy recovery • finallylandfill/scuttle • only if all else fails.

  11. 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

  12. Plastic Resin Identification Codes PA6 GF30/M20 FR: • polyamide-6(caprolactam-based nylon) • 30% glass fibre • 20% mineral filler • flame retardant recycled black PET ... but issues sorting with NIR Image from https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQs4fw_Et1SrkcTlxv4NmDH6bj67sD-oX3-rsGIX5XxHtQMMC2F

  13. Directive 2019/904:reduction of the impact of certain plastic products on the environment • “items that fall under this [single-use plastic] ban include single-use products made of plastic to which alternatives exist on the market, such as • cotton bud sticks, cutlery, plates, straws, stirrers, sticks for balloons, … cups, food and beverage containers • made of expanded polystyrene and all products made of oxo-degradable plastic”. http://news.bio-based.eu/open-letter-to-dg-environment-which-polymers-are-natural-polymers-in-the-sense-of-the-single-use-plastic-ban/

  14. An alternative is composting for bio-based materials • composting: biodegradation of polymers under controlled composting conditions • determined using standard methods including ASTM D5338 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.

  15. 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.

  16. 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)

  17. 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

  18. 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?

  19. 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

  20. Burnt fibre diameters vs original diameters • overall fiber diameter reduced drastically inside the flame after fibers released from composite. • mean diameter: • burnt fibres 4.2 µm • virgin fibers 7 µm • flame temperatures(>900°C) and O2-rich,many fiberscompletely consumed. US DOT/FAA/AR-98/34, 1998 Health hazards of combustion productsfrom aircraft composite materials

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

  22. Environmental ImpactClassification Factors:

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

  24. Summary • raw materials • production • fitness for purpose • end-of-use • Life Cycle Assessment (LCA)

  25. 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.

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