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

2. 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 Aramid (K49) 1440 124 2.5 2760 11.9 High-strain CF 1820 200 1.3 2550 8.2 High-mod CF 2020 379 0.5 1720 11.0

3. 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:

4. 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

5. 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 • viahttp://www.flaxcouncil.ca/images

6. 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

7. 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 lineshttp://www.chanvre-info.ch/info/en/article581.html • Marianne Leupin: New processing with hemp http://www.texma.org/hemp1.pdf

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. Crop Index • Purdue UniversityCenter for New Crops and Plant Products crops are listed alphabetically by genus and common namehttp://www.hort.purdue.edu/newcrop/Indices/index_ab.html

16. 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

17. 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

18. 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 ?