Transcript 564 KB - Plymouth

Environmental implications
of composites
John Summerscales
Outline of lecture
•
•
•
•
raw materials
production
fitness for purpose
end-of-use
Consumption of materials
Material
Production/Consumption (Mega Tonnes)
Date
Steel
1107
2005
Aluminium
23.4
2005
Copper
12.4
2003
Zinc
>10
2005
Timber EU-25
21.8
2003
Timber UK
7.5
2004
Plastics
100
2006
>300
20101
Plastics UK
4.7
2002
Bio-based polymers
0.7
20102
Bio-based polymers
1.7
20152
Composites WEur
1.54
2000
Composites UK
0.21
2000
Plastics
1: http://dx.doi.org/10.1016/j.progpolymsci.2013.05.006
2: http://dx.doi.org/10.1016/j.eurpolymj.2013.07.025
Mtonnes of composites in USA
Raw materials
• Thermoplastics, resins,
carbon fibre, aramid fibres
primary feedstock = oil
o potential for coal as feedstock
o bio-based feedstocks
o

e.g. carbon fibres from rayon (cellulose)
• Glass (or basalt) fibres
o
primary feedstock = minerals
Production of materials
• carbon fibres pyrolysed at 1000-3000°C*
higher temperatures for higher modulus
o greenhouse gases produced
o
• aramid fibres spun from conc.H2SO4 solution
o
strong acid required to keep aramid in solution
• glass fibres spun from “melt” at ~1375°C
o
greenhouse gases produced
http://www.answers.com/topic/carbon-fiber
http://www.answers.com/topic/kevlar
http://www.answers.com/topic/fiberglass
Component manufacture
• Net-shape production?
knitted preforms
o closed mould to avoid “overspray” or equivalent
o dry fibres and wet resin (infusion vs prepreg)
o
for aerospace prepreg manufacture
up to ~40% of material from roll may go to waste
because fragment size and orientation not useful
 resin film infusion uses unreinforced resin
so orientation is not an issue
and % usage only limited by labour costs

Fitness for purpose
• does lightweight structure
reduce fuel consumption?
• what is the normal product lifetime?
o
can it be designed for extended life/ re-use etc
• do safety factors
unnecessarily increase materials usage?
End of life: hierarchy of options:
• first re-use
o
consider re-use (or dis-assembly or recycling)
at the design state
• re-cycle
o
o
o
difficult to de-ply laminated composites
high Vf composites may need dilution with additional matrix material
potential for comminuted waste as filler
• decomposition
o
o
o
pyrolysis/hydrolysis etc
for materials recovery, e.g. Milled Carbon Ltd.
future: enzymes, ionic liquids, sub- and super-critical processes
• incineration
o
with energy recovery
• finally landfill
o
only if all else fails.
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
Plastic Resin Identification Codes
PA6 GF30/M20 FR:
• polyamide-6
(caprolactam-based nylon)
• 30% glass fibre
• 20% mineral filler
• flame retardant
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
o
aerobic (with air present):

o
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.
Digestion vs Composting
bacteria (no fungi)
Anaerobic digestor
Aerobic composting
bacteria and fungi
temperature:
50-60°C
chemical pulp - starch starch/PCL- PHA - PLA
thermophilic digestion
industrial composting
chemical pulp - mechanical pulp starch - starch/PCL - PBAT -PHA - PLA
temperature:
≤35°C
chemical pulp - starch starch/PCL- PHA
mesophilic digestion
home composting
chemical pulp - mechanical pulp starch - starch/PCL - PBAT -PHA
outputs
CO2 - humus
digestate
compost
CO2 - CH4 - N2O - humus
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.
Political drivers (EC)
• End of Life Vehicles (ELV) Directive
(2000/53/EC)
last owners must be able to deliver their vehicle
to an Authorised Treatment Facility
free of charge from 2007
o sets recovery and recycling targets
o restricts the use of certain heavy metals
in new vehicles
o
• Waste Electrical and Electronic Equipment
(WEEE) Directive (2002/96/EC)
ELV targets
• end of life vehicles generate 8-9 Mtonnes
of waste/year in the European Community
• 2006:
85% re-use and recovery
o 15% landfill
o
• 2015:
95% re-use and recovery
o 5% landfill
o
ELV targets
• ELV targets were set to minimise landfill
• total lifetime costs may be increased
e.g. for composites:
o thermoset manufactured at use temperature
o

o
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?

Carbon fibres: incineration
• carbon fibres should burn to CO2
in 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 risk
of inhalable fibres released from
burning carbon composite transport structures
Life Cycle Assessment
ISO14040 series standards
• The goal & scope definition
• Life Cycle Inventory analysis (LCI)
• Life Cycle Impact Assessment (LCIA)
• Life Cycle Interpretation
Environmental Impact
Classification Factors:
ISO/TR 14047:2003(E)
Azapagic et al
Acidification
Acidification Potential (AP)
Ecotoxicity
Aquatic Toxicity Potential (ATP)
Eutrophication / Nitrification
Eutrophication Potential (EP)
Climate Change
Global Warming Potential (GWP)
Human Toxicity
Human Toxicity Potential (HTP)
Depletion of abiotic /biotic resources
Non-Renewable / Abiotic Resource
Depletion (NRADP)
Stratospheric ozone depletion
Ozone Depletion Potential (ODP)
Photo-oxidant formation
Photochemical Oxidants Creation
Potential (POCP)
Draft BS8905 adds Land Use
Environmental Impact Classification Factor
(analysis by Nilmini Dissanayake)
Acidification Potential (AP)
Aquatic Toxicity Potential (ATP)
Eutrophication Potential (EP)
Global Warming Potential (GWP)
Human Toxicity Potential (HTP)
Non-Renewable/Abiotic Resource Depletion (NRADP)
Ozone Depletion Potential (ODP)
Photochemical Oxidants Creation Potential (POCP)
Noise and Vibration
Odour
Loss of biodiversity
Fugitive Dust
KEY
Very High Effect
Low Effect
No Effect
Fabrication
Packaging
Problem?
Issue?
No impact?
Raw material handling
Raw material storage
Crushing
Weighing
Mixing
Melting
Refining
Forming
Sizing
Binding
Spinning
Oven Drying
Oven Curing
Environmental Impact for
Glass fibre production:
Recommended further reading
• Y Leterrier, Life Cycle Engineering of Composites,
Comprehensive Composite Materials Volume 2,
Elsevier, 2000, 1073-1102.
• W McDonough and M Braungart
Cradle 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.