Transcript Natural fibres as reinforcements for composites

Natural fibres as
reinforcements
for 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
Natural fibre properties
Natural
Density Modulus Elongn
(kg/m3) (GPa)
(%)
Strength Diameter
(MPa)
(μm)
Silk
1340
10
18-20
600
Coir
Cotton
1150
1520
4-6
27
15-40
6-12
131-175 100-450
200-800
Pineapple
1450
1440
10-22
35-82
3-7
1.6
530-640 50-300
413-1627 20-80
Flax
Hemp
Jute
Kenaf
1520
1520
1520
1400
100
70
60
53
1.8
1.7
2.0
840
920
860
930
2550
2500
1440
1820
2020
71
85
124
200
379
3.4
4.6
2.5
1.3
0.5
3400
4580
2760
2550
1720
Animal
Seed
Leaf
Sisal
Stem (bast)
Man-made fibres
E-glass
S-glass
Aramid (K49)
High-strain CF
High-mod CF
200
11.9
8.2
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:
E-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
Materials
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 Applications
http://www.ienica.net/crops/flax.pdf
http://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 hemp
http://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
Jute
Corchorus capsularis. L. - white jute
C. olitorius L. - Tossa jute.
• The Golden Fibre
http://www.bdcom-online.com/shathi/jute.htm
• Biotechnology in jute fibre processing
http://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 1991
http://corn.agronomy.wisc.edu/alternativecrops/Kenaf.htm
•
Charles S Taylor
Kenaf: an emerging new crop industry, 1993 (in New Crops, 1993)
http://www.hort.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/proceedings1996/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/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 Technology
http://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 University
Center 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 ?