Natural fibres as reinforcements for composites

1
Natural fibres as reinforcementsfor composites

• Richard Cullen
• and John Summerscales

Flax Field, Providence by Hazel Barker From
http//www.art.com/asp/sp-asp/_/pd--10125356/Flax_
Field_Providence.htm
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Natural fibre properties

• Natural Density Modulus Elongn Strength Diameter
  
• (kg/m3) (GPa) () (MPa) (µm)
• Animal
• Silk 1340 10 18-20 600
• Seed
• Coir 1150 4-6 15-40 131-175 100-450
• Cotton 1520 27 6-12 200-800
• Leaf
• Sisal 1450 10-22 3-7 530-640 50-300
• Pineapple 1440 35-82 1.6 413-1627 20-80
• Stem (bast)
• Flax 1520 100 1.8 840
• Hemp 1520 70 1.7 920
• Jute 1520 60 2.0 860 200
• Kenaf 1400 53 930
• Man-made fibres
• E-glass 2550 71 3.4 3400
• S-glass 2500 85 4.6 4580

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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

Materials E-modulus (GPa) UTS (MPa) Elongation ()
Q Queens flax 13455 14166 1.140.4
S Silsoe flax 11778 9353 1.230.51
H Seale-Hayne linseed 7953 7150 1.360.49
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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

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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

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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/003f
  lax.html

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Hemp (Cannabis sativa L.)

• Physical , Chemical and Pulping Characteristics
  of Hemp http//www.forestry.utoronto.ca/wood/fat
  ima.htm
• Michael Karus European hemp industry 2001
  cultivation, processing, and product lines
  http//www.chanvre-info.ch/info/en/article581.ht
  ml
• Marianne Leupin New processing with
  hemp http//www.texma.org/hemp1.pdf

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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

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

• The Golden Fibrehttp//www.bdcom-online.com/shath
  i/jute.htm
• Biotechnology in jute fibre processinghttp//www.
  epbbd.com/month23/Background.htm

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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

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Kenaf

• PJ LeMahieu, ES Oplinger and DH
  Putnam Alternative Field Crops Manual Kenaf,
  April 1991 http//corn.agronomy.wisc.edu/alternat
  ivecrops/Kenaf.htm
• Charles S Taylor Kenaf an emerging new crop
  industry, 1993 (in New Crops, 1993) http//www.hor
  t.purdue.edu/newcrop/proceedings/v2-402.html
• Daniel E Kugler Kenaf commercialisation
  1986-1995 (in Progress in New Crops, 1996)
  http//www.hort.purdue.edu/newcrop/proceedings199
  6/v3-129.html
• T Sellers, GD Miller, MJ Fuller, JG Broder and
  RR. Loper Lignocellulosic-Based Composites Made
  of Core From Kenaf An Annual Agricultural
  Crop http//www.ersac.umn.edu/iufro/iufronet/d5/w
  u50501/pu50501.htm

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Nettle (Urtica dioica)

• Nettles yield 8-10 tonnes fibre/acre
  http//jacksonsrow.topcities.com/tikun_olam/nettl
  e.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

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Nettle

• 24 v/o nettle/epoxy E/s 9 GPa/91 MPa
• 23 v/o nettle/phenolic E/s 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

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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

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Crop Index

• Purdue UniversityCenter for New Crops and Plant
  Products crops are listed alphabetically by genus
  and common name http//www.hort.purdue.edu/newcro
  p/Indices/index_ab.html

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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

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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

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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 ?