Fibres are the raw material from which textiles are made for clothing ,household,floor covering and industrial uses . For convenience fibres are generally classified as being either natural or manmade ,that is formed by chemical processes ,usually involving extrusion of the fibre .
In 1971 the ‘free ‘ world production of natural fibres was estimated at 17,832,000 tons , while manmade fibres was 8, 415,000 tons . Natural fibre production ,however was stable or increased only slightly in the years 1950- 1971 , while manmade production expanded steadily ,with a fourfold increase in the period . When manmade fibres have relied on petrochemical expansion which is currently in question ,natural fibre production expansion is difficult owing to high production costs and competition for land utilization .
The use of natural fibres goes back to the Stone Age when flax and hemp were exploited . Eventually wool ,silk and cotton fibres were discovered and were known to have been in use for several thousand years BC . In mediaeval times wool processing was a major occupation ,but industrial processing ,involving mainly wool and cotton dates from about 1750 .
In modern times ,all three natural kingdoms ,animal ,vegetable and mineral ,supply textile fibres . Natural fibres are the essential alternative in the ever expanding horizon of textile fibres . Natural fibres are becoming the essential necessity and are available abundantly . They are non-toxic in nature besides ; the disposal of fibre wastes is easier as they are necessarily biodegradable . Bast fibre and leaf fibre are already in use in plenty in the textile industry. But till date no much work is done on seed and fruit fibres like Coir/Coconut , Tree Cotton, Java Kapok , Balsa fibre , Milkweeds , etc.
Coconut is the main crop cultivated in Lakshadweep . It is India ‘s largest producer of coconuts . About 2,598 hectares are under coconut cultivation and the productivity per hectare is 22,310 . Coir fibre producer are based in Tamil Nadu . They export to China, Taiwan , Malaysia. The biggest exporter is Sunco Exporters Pvt Ltd , Pollachi ,Tamil Nadu . Segregation of coir fibre is done in Allepy ,Kerala.
Total world coir fibre production is 250,000 tonnes . The coir fibre industry is particularly important in some areas of the developing world . India ,mainly the coastal region of Kerala State , produces 60 % of the total world supply of white coir fibre . Sri Lanka produces 36 % of the total world brown fibre output . Over 50 % of the coir fibre produced annually throughput the world is consumed in the countries of origin , mainly India . Together India and Sri Lanka produce 90 % of the 250,000 metric tons of coir produced every year .
As per the Coir Board ,India has a bilateral trade agreement dating back to 1956 with Chile .
Production and Processing –
Coir is a coarse fibre which comes from the husks of coconuts . In other words coir is Cocos nucifera and is obtained from the husk surrounding the nut ,that is the fruit of the coconut plant .
The husks are quartered and put in large water tanks and weighted with a network of iron rails . After five days the husks are removed and run through a machine composed of two corrugated iron rollers that crushes them and prepares them for the next machine , called the drum . The husks are held against the revolving drums and the spikes tear out the woody part , leaving the long ,coarse fibres separated . The fibres are then made into hanks .
Coconuts are the seed of the palm trees . These palms flower on a monthly basis and the fruit takes 1 year to ripen. A typical palm tree has fruit in every stage of maturity .A mature tree can produce 50 – 100 coconuts per year . Coconuts can be harvested from the ground once they have ripened and fallen or they can be harvested while still on the tree . A human climber can harvest approximately 25 trees in a day , while a knife attached to a pole can up the number to 250 trees harvested in a day . Monkeys can also be trained to harvest the coconuts , but this practice is less efficient than other methods .Green coconuts , harvested after about six to twelve months on the plant , contain pliable white fibres . Brown fibre is obtained by harvesting fully mature coconuts when the nutritious layer surrounding the seed is ready to be processed into copra and desiccated coconut . The fibrous layer of the fruit is then separated from the hard shell ( manually) by driving the fruit down onto a spike to split it ( De – husking) . A well seasoned husker can manually separate 2,000 coconuts per day . Machines are now available which crush the whole fruit to give the loose fibres . These machines can do up to 2,000 coconuts per hour .
The fibrous husks are soaked in pits or in nets in a slow moving body of water to swell and soften the fibres . The long bristle fibres are separated from the shorter mattress fibres underneath the skin of the nut ,a process known as wet-milling . The mattress fibres are shifted to remove dirt and other rubbish ,dried in the sun and packed into bales . Some mattress fibre is allowed to retain more moisture so that it retains its elasticity for ‘twisted ‘ fibre production . The coir fibre is elastic enough to twist without breaking and it holds a curl as though permanently waved . Twisting is done by simply making a rope of the hank of fibre and twisting it using a machine or by hand . The longer bristle fibre is washed in clean water and then dried before being tied into bundles or hunks . It may then be cleaned and ‘ hackled ‘ by steel combs to straighten the fibres and remove any shorter fibre pieces . Coir bristle fibre can also be bleached and dyed to obtain hanks of different colours.
The immature husks are suspended in a river or water –filled pit for up to ten months . During this time micro-organisms break down the plant tissues surrounding the fibres to loosen them – a process known as retting . Segments of the husk are then beaten by hand to separate out the long fibres which are subsequently dried and cleaned . Cleaned fibre is ready for spinning into yarn using a simple one-handed system or spinning wheel.
The coir fibre can be dyed using reactive dyes,vat dyes and sulphur dyes. It can be bleached using hydrogen peroxide. When dyed black , coir fibre looks very much like horse hair.
Structure and Properties –
It is Coarse . Dark brown colour . Individual fibres short ; 0.5 mm ( 1/50 th inch ) long . Thick walled with irregular lumen . Surface covered with pores . Coir fibres are found between the husk and the outer shell of a coconut . The individual fibre cells are narrow and hollow ,with thick walls made of cellulose . They are pale when immature but later become hardened and yellowed as a layer of lignin is deposited on their walls . There are two varieties of coir
1. Brown Coir – It is harvested from fully ripened coconuts . It is thick, strong and has high abrasion resistance . It is typically used in mats ,brushes and sacking . Mature brown coir fibres contain more lignin and less cellulose than fibres such as flax and cotton and so are stronger but less flexible.They are made up of small threads ,each about 1mm long and 10 to 20 micrometers in diameter .
2. White coir – The fibres are harvested from the coconuts before they are ripe . These fibres are white or light brown in colour and are smoother and finer ,but also weaker . They are generally spun to make yarn that is used in mats or rope .
The coir fibre is relatively water –proof and is one of the few natural fibres resistant to damage by salt water . Fresh water is used to process brown coir ,while sea water and fresh water are both used in the production of white coir.
In the form in which it is taken from the coconut husk , coir fibre is composed of a number of reddish-brown ,strong,elastic filaments of different lengths, which are thickest in the middle of their length and taper towards the ends : in cross-section they are round or elliptical . The diameter in the middle varies from 0.002 to 0.012 inches. These filaments , however , are each made up of a number of irregularly –thickened ultimate fibre cells which vary in length from about 0.4 to 1 mm and have a diameter of 5 to 8 microns .
|Type of fibre||Tensile strength ( MPa)||Elongation ( % )||Toughness (MN/m2)|
Coir fibres and yarns are used for making coarse cloths and bristles for brushes. It is used for cordages ,matting, brushes . Coir is also used geo textiles . It provides a low impact and affordable solution to the problems of soil erosion and land sliding . It has been laid along the land adjoining the Konkan Railway track . For natural geo –textiles , coir is still preferred to jute , as it possesses strength , durability and high content of lignin . Moreover , for geotextiles , it is not necessary to have a similar shade of coir yarn. It is used for brush-making ,door mats , fish nets , cordage .
Brown coir is used in floor mats and doormats , brushes , mattresses , floor tiles and sacking . A small amount is also made into twine . Pads of curled brown coir fibre , made by needle –felting ( a machine technique that mats the fibres togother ) are shaped and cut to fill mattresses and for use in erosion control on river banks and hill sides . A major proportion of brown coir pads are sprayed with rubber latex which bonds the fibres togother ( rubberized coir) to be used as upholstery padding for the automobile industry in Europe . The material is also used for insulation and packaging.
The major use of white coir is in rope manufacture . Mats of woven coir fibre are made from the finer grades of bristle and white fibre using hand or mechanical looms. White coir also used to make fishing nets due to its strong resilience to salt water .
In horticulture , coir is recommended as substitute for sphagnum moss because it is free of bacteria and fungal spores , and is sustainably produced without the environmental damage caused by pelt mining . Coconut coir from Mexico has been found to contain large numbers of colonies of the beneficial fungus Aspergillus terreus which acts as a biological control against plant pathogenic fungi.
Coir fibres make up about 1/3 of the coconut pulp . The other 2/3 is called the pith or dust , it is biodegradable but takes 20 years to decompose . Once considered as waste material , coir is now being used as mulch, soil treatment and a hydroponic growth medium .
India is promoting through Coir Board various products like Coir geo textiles and Coir Ply besides products like floor mats and coverings. India exports to Chile coir products worth 375.43 tonnes valued at Rs 2.54 crores in 2007.
Indian spinning mills should try to add coconut fibre in dyed or grey form along with other cellulosic or synthetic fibre in different proportion and make fancy yarns . It can be tried as a replacement for costly flax and ramie fibres.