Natural fibres as reinforcementsfor composites

Richard Cullenand John

Summerscales

Flax Field, Providence by Hazel BarkerFrom

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

Natural fibre propertiesNatural Density ModulusElongn Strength

Diameter (kg/m3) (GPa) (%) (MPa) (μm)

AnimalSilk 1340 10 18-20 600

SeedCoir 1150 4-6 15-40 131-175 100-450Cotton 1520 27 6-12 200-800

LeafSisal 1450 10-22 3-7 530-640 50-300Pineapple 1440 35-82 1.6 413-162720-80

Stem (bast)Flax 1520 100 1.8 840Hemp 1520 70 1.7 920Jute 1520 60 2.0 860 200Kenaf 1400 53 930

Man-made fibresE-glass 2550 71 3.4 3400S-glass 2500 85 4.6 4580Aramid (K49) 1440 124 2.5 2760 11.9High-strain CF 1820 200 1.3 2550 8.2High-mod CF 2020 379 0.5 1720 11.0

Flax/Linseed (Linum usitatissimum L.)• Cultivars bred with an emphasis on

either:– fibre (flax), or– seed (linseed)

• 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

Growth stages (GS)

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

• cotyledon to growing point emerged– Growth stages 3 & 4

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

– Growth stage 5• stem extension

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

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

– Growth stage 12• seed ripe

Growth stages

Life cycle of the flax plant consists of

• a 45 to 60 day vegetative period,

• a 15 to 25 day flowering period and

• a maturation period of 30 to 40 days

From J A Turner “Linseed Law” BASF (UK) Limited, 1987

via http://www.flaxcouncil.ca/images

Key resources

• Flax Council of Canada http://www.flaxcouncil.ca/

• Interactive European Network for Industrial Crops and their Applicationshttp://www.ienica.net/crops/flax.pdfhttp://www.ienica.net/crops/linseed.pdf

• Flax (Linen)http://www.swicofil.com/products/003flax.html

Hemp (Cannabis sativa L.)

• Physical , Chemical and Pulping Characteristics of Hemp

http://www.forestry.utoronto.ca/wood/fatima.htm• Michael Karus: European hemp industry 2001:

cultivation, processing, and product lines

http://www.chanvre-info.ch/info/en/article581.html

• Marianne Leupin: New processing with hemphttp://www.texma.org/hemp1.pdf

Jute (Corchorus)

• Corchorus capsularis. L. - white jute

• Corchorus olitorius L. - Tossa jute.– second most common natural fibre, next to

cotton, cultivated in the world – grown in Bangladesh, Brazil, China, India,

Indonesia

JuteCorchorus capsularis. L. - white juteC. olitorius L. - Tossa jute.

• The Golden Fibrehttp://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

Kenaf• PJ LeMahieu, ES Oplinger and DH Putnam

Alternative Field Crops Manual: Kenaf, April 1991http://corn.agronomy.wisc.edu/alternativecrops/Kenaf.htm

• Charles S TaylorKenaf: an emerging new crop industry, 1993 (in New Crops,

1993) http://www.hort.purdue.edu/newcrop/proceedings/v2-402.html

• Daniel E KuglerKenaf commercialisation: 1986-1995 (in Progress in New

Crops, 1996) http://www.hort.purdue.edu/newcrop/proceedings1996/v3-129.html

• T Sellers, GD Miller, MJ Fuller, JG Broder and RR. LoperLignocellulosic-Based Composites Made of Core From Kenaf:An Annual Agricultural Crop

http://www.ersac.umn.edu/iufro/iufronet/d5/wu50501/pu50501.htm

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 stiffness

are 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

STING

• Sustainable Technology In Nettle Growing

• STING is a three and a half year LINK project sponsored by Defra through the Sustainable Technologies Initiative

• Co-ordinated by De Montfort University

Crop Index

• Purdue UniversityCenter for New Crops and Plant Products crops are listed alphabetically by genus and

common name http://www.hort.purdue.edu/newcrop/Indices/index_ab.html

From plant to fibre• Harvest (combining or pulling)• Retting (dew-, wet-, stand- or enzyme-

retting)– enzymes (e.g. pectinase digests pectin binder)

• Decortication (scutching)– Hammer mill– Fluted rollers– Willower

• Cleaning (removal of shive)• Carding (brushing/combing to align fibres)

– product is known as sliver

• Spinning (twisting to bind the fibres)– product is known as yarn or filaments

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

The future ?

• Extracting fibre without damage• Effective coupling agents

– cellulose chemistry instead of silanes

• Environmental durability – barriers to prevent moisture absorption– sterilise fibres to prevent

biodeterioration

• Other issues ?