Sustainable composites

John Summerscales

Sustainability

Brundtland Commission Report (1987)The World Commission on Environment and Development suggested the following definition of Sustainable Development:"Meeting the needs of the present without compromising the ability

of future generations to meet their own needs."

Sustainability

• Bruntland emphasised the need to balance:o economicso environmento socialo governance

• Now generally reduced to “Triple E”o Economyo Ecologyo Equity

Sustainable composites

This lecturedescribes materials from natural sources,

without prejudice to the results of any future Quantitative Life Cycle Analysis (QLCA)which may (or may not) make the case for these materials being more environmentally-friendlythan equivalent systems manufactured from man-made fibres and synthetic resins. 

Typical fibre properties

• The data on the next three slides is from:o NL Hancox, Fibre Composite Hybrid Materials,

Elsevier Applied Science, Barking, 1981.

o TJ Reinhart, Engineered Materials Handbook 1: Composites, ASM International, 1987.

o Chand et al, Journal of Materials Science,1988, 23(2), 381-387.

• where a range is given in the references,the arithmetic mean is shown in the graph

Density of fibresBast (plant stem) Leaf Seed Animal Synthetic

Carb

on

Ara

mid

Gla

ss

Silk

Coir

Cotto

n

Sisa

l

Pin

eap

ple

Jute

Hem

p

Flax

1500 kg/m3

Young’s moduli of fibres

Carb

on

Ara

mid

Gla

ss

Silk

Coir

Cotto

n

Sisa

l

Pin

eap

ple

Jute

Hem

p

Flax

Bast (plant stem)

Leaf

Seed

Animal

Synthetic

100 GPa

Strengths of fibres

1 GPa

Bast (plant stem)

Leaf

Seed

Animal

Synthetic

3 GPa

2 GPa

Carb

on

Ara

mid

Gla

ss

Silk

Coir .

Cotto

n

Sisa

l

Pin

eap

ple

Jute

Hem

p

Flax

Fibre specific moduli and strengths• Specific value is (modulus or

strength)/densityo i.e. (MN/m2)/(kg/m3) = MN.m/kgModulus Strength

Flax 65.8 0.55

Hemp 46.1 0.61

Jute 39.5 0.57

Glass 27.8 1.33

Aramid 86.1 1.92

Carbon 109.9 1.40

Aluminium 25.5

Flax/Linseed (Linum usitatissimum L.)

• Mike Felstead: Flax and linseed fibres as reinforcement for epoxy composites,BEng Composites, June 1995.

MaterialsE-

modulus (GPa)

UTS(MPa)

Elongation (%)

Q: Queens flax 134±55 141±66 1.14±0.4

S: Silsoe flax 117±78 93±53 1.23±0.51

H: Seale-Hayne linseed 79±53 71±50 1.36±0.49

Flax

Flax Field, Providence by Hazel BarkerFrom

http://www.art.com/asp/sp-asp/_/pd--10125356/Flax_Field_Providence.htm

Flax and linseed are cultivars grown for fibre or seedrespectively

Flax: growth stages

• 12 distinct growth stages in the flax plant:o Growth stages 1 & 2

cotyledon (seed leaf) to growing point emergedo Growth stages 3 & 4

1st pair of true leaves unfolded to third pair of true leaves unfolded

o Growth stage 5 stem extension

o Growth stages 6, 7, & 8 buds visible to full flower

o Growth stages 9, 10 & 11 late flower to brown capsule

o Growth stage 12 seed ripe

FLAX: growth stagesLife cycle of the flax plant consists of

• a 45-60 day vegetative period,

• a 15-25 day flowering period, and

• a maturation period of 30 to 40 days

J A Turner “Linseed Law” BASF (UK) Limited, 1987 via http://www.flaxcouncil.ca/images

Flax: from plant to fabric• harvest (combining or pulling)• retting (dew-, wet-, stand- or enzyme-retting)

o enzymes (e.g. pectinase digests pectin binder)

• decortication (scutching)o Hammer millo Fluted rollerso Willower

• cleaning (removal of shive)• carding (brushing/combing aligns fibres) > sliver• spinning (twisting binds fibres) > yarn/filament• weaving, braiding, knitting, etc

Hemp (Cannabis sativa L.) • annual plant native to central Asia and

grown in China over 4500 years ago.• probably reached central Europe in the

Iron Age (circa 400 BC) • evidence of growth in the UK

by the Anglo-Saxons (800-1000 AD).• does not require fertiliser, herbicides or

pesticides to grow well• in suitable warm conditions,

it can grow to 4 metres in just 12 weeks.

Hemp (Cannabis sativa L.)

Disadvantage?• some strains of this plant are ...

psychotropicpsychotropic• those good for the above are not best for

fibre• ... but good fibre plant can be used to

disguise plants grown for drugs• new strains of fibre plant with distinctive

leaf colours are under development

Henry Ford car 1941hemp and flax

fibres used in resin matrix composites for body of Henry Ford car able to withstand ten-times the impact on an equivalent metal panel

Video

Henry Ford tries out his first carmade from plant based materials"the axe bounced, and there was no dent"

Image fro

m h

ttp://w

ww

.chanvre

-info

.ch/in

fo/e

n/A

bout-H

enry

-Ford

-s-C

ar.h

tml

JuteCorchorus capsularis. L. - white juteC. olitorius L. - Tossa jute. • The Golden Fibre

http://www.bdcom-online.com/shathi/jute.htm

• Biotechnology in jute fibre processinghttp://www.epbbd.com/month23/Background.htm

Kenaf (Hibiscus cannabinus L.)• fibre plant native to east-central Africa.• common wild plant of tropical and

subtropical Africa and Asia• grown for several thousand years for

food and fibre• unique combination of

long bast and short core fibres• two crops/year in Malaysia

Nettle (Urtica dioica)

• Nettles yield ~ 8-10 tonnes fibre/acre http://jacksonsrow.topcities.com/tikun_olam/nettle.html

• far stronger than cotton but is finer than other bast fibres such as hemp

• much more environmentally friendly fibre crop than cotton, which requires more irrigation and agrochemical input

Nettle • 24 v/o nettle/epoxy E/σ’ = 9 GPa/91 MPa• 23 v/o nettle/phenolic E/σ’ = 5 GPa/13MPa• 21 v/o flax/epoxy

“strength and stiffnessare more than twice as high”

Ann-Jeanette Merilä, Stinging nettle fibres as reinforcement in thermoset matrices, MSc Engineering/Materials Technology, Luleå University of Technologyhttp://epubl.luth.se/1402-1617/2000/235/index-en.html

Rules-of-mixture for NFRP

• Young’s modulus:o Ec = κηdηlηoVfEf + VmEm

• Strength:o σ’ = κVfσf’ + Vmσm*

• κ = fibre area correction factor

• ηd = fibre diameter distribution factor

κ = fibre area correction factorηd = fibre diameter distribution factor

• κ corrects for true area or irregular CSAwhen apparent fibre diameter is measured

• ηd = fibre diameter distribution factoro data below from Christophe Baley at USB

Environmental issues• Depletion of soil nutrients/fertiliser• Competition from weeds/herbicides• Competition from animals/pesticides

Economic issues• Agricultural subsidies• Dependence on weather• Market price vs other producers

Are natural fibres good?

Are natural fibres good?

• “natural fibre production requires less than 10 percent of the energy used for production of PP fibres (around 90 GJ/tonne)”, but .....

JEG van Dam and HL Bos, Consultation on natural fibres:the environmental impact of hard fibres and jute in non-textile industrial applications ESC-Fibres Consultation no 04/4, Rome, 15-16 December 2004.

Are natural fibres good?

..... that data is total energy input for jute fibre cultivation (excluding field labour, retting and decortication)when grown by numerous small farmers utilising labour and animal power with limited agrochemicals and machinery

Are natural fibres good?Data from TexFlax project thesis for flax:• ploughed• seed sown• pesticide applied (twice)• N applied• P/K applied• herbicide applied (twice)• harvestedHow much fuel went through the tractor, and how much energy was in the sprayed materials?

Life Cycle Assessment• Four different phases [Brady]:

o Goal and scope definition: in the context of the intended application.

o Inventory analysis: collect data, quantifies relevant inputs and outputs.

o Impact assessment: translates inventory analysis into impactsevaluating significance of the respective impacts.

o Interpretation: conclusions and recommendations for decision makers

Quantitative life cycle assessment (QLCA)

Adisa Azapagic• Environmental impact classification factors:

1. Non-Renewable/Abiotic Resource Depletion (NRADP)

2. Global Warming Potential (GWP) 3. Ozone Depletion Potential (ODP) 4. Acidification Potential (AP) 5. Eutrophication Potential (EP) 6. Photochemical Oxidants Creation Potential (POCP) 7. Human Toxicity Potential (HTP) 8. Aquatic Toxicity Potential (ATP)

Nilmini’s interim analysisEnvironmental Impact for Flax fibre:

See also http://www.netcomposites.com/downloads/03Thurs_Summerscales.pdf - slide 15

Environmental burdens: flax

• embodied energies for flax (no-till agriculture):o 54 GJ/tonne for sliver (55 GJ/tonne for glass mat)o 80 GJ/tonne for yarn (32 GJ/tonne for continuous

glass)

minimum < middle < maximum• no till < conservation agriculture

< mouldboard plough• organic fertiliser < agro-chemicals• biological control of pests

< pesticides• water- < dew- < bio-retting• sliver < spun yarn

QLCA: Le Duigou vs Dissanayake

Key differences:•Higher level of nuclear power in the French energy mix•UK plants desiccated at mid-point flowering but French plants allowed to set seed•UK yield only 6000 kg/ha but French yield 7500 kg/ha at harvest•UK study excluded photosynthesis and CO2 sequestration•UK study allocated all burdens to fiber

French study allocated on mass of productas a proportion of all (co-)products

The future ?

• Extracting fibre without damage• Effective coupling agents

o cellulose chemistry instead of silanes

• Environmental durability o barriers to prevent moisture absorptiono sterilise fibres to prevent biodeterioration

• Quantitative Life Cycle Assessment (QLCA)• Other issues ?• BS8905 adds “Land Use” as 9th EICF

• growing food vs fuel, feedstock, fibre

Bio-based resin systemsThermoplastics• CPLA (polylactide aliphatic copolymer)• PCL (polycaprolactone) • PGA (polyglycolicacid)• PHA (polyhydroxyalkanoate)

o PHB (poly-beta-hydroxybutyrate)o PHBV (polyhydroxybutyrate-valerate)

• PLA (polylactide) • DuPontTM Sorona®

Bio-based resin systems

Thermosets• Acrylised epoxidised soybean oil

(Aropol Envirez 5000, UCB Ebecryl)• Cashew Nut Shell Liquid (CNSL)• Epoxidised linseed oil

.. and .. polycarboxylic acid anhydrides• Partially norbornylized linseed oil

(Dilulin®)• Rapeseed-oil derived resins

Summary

• sustainability• natural fibres

o bast (stem), leaf, seed, animalo temperate or tropical zoneo growth, harvest, retting, separation, etc

• life cycle assessment (ISO 14040 series)• environmental impacts (8 EICF + land

use)• bio-based resins