Coir (/ˈkɔɪər/), also called coconut fibre, is a natural fibre extracted from the outer husk of coconut[1] and used in products such as floor mats, doormats, brushes, and mattresses. Coir is the fibrous material found between the hard, internal shell and the outer coat of a coconut. Other uses of brown coir (made from ripe coconut) are in upholstery padding, sacking and horticulture. White coir, harvested from unripe coconuts, is used for making finer brushes, string, rope and fishing nets.[2] It has the advantage of not sinking, so can be used in long lengths in deep water without the added weight dragging down boats and buoys.
The name coir comes from கயற (kayiru), കയർ (kayar), the Tamil and Malayalam words respectively for cord or rope (traditionally, a kind of rope is made from the coconut fibre).[6][7] Ropes and cordage have been made from coconut fibre since ancient times. The Austronesian peoples, who first domesticated coconuts, used coconut fibre extensively for ropes and sennit in building houses and lashed-lug plank boats in their voyages in both the Pacific and the Indian Oceans.[8][9][10][11]
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Coir fibres are found between the hard, internal shell and the outer coat 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.[14] Each cell is about 1 mm (0.04 in) long and 10 to 20 μm (0.0004 to 0.0008 in) in diameter.[15] Fibres are typically 10 to 30 centimetres (4 to 12 in) long.[5] The two varieties of coir are brown and white. Brown coir harvested from fully ripened coconuts is thick, strong and has high abrasion resistance.[14] It is typically used in mats, brushes and sacking.[14] Mature brown coir fibres contain more lignin and less cellulose than fibres such as flax and cotton, so are stronger but less flexible. White coir fibres harvested from coconuts before they are ripe are white or light brown in color and are smoother and finer, but also weaker. They are generally spun to make yarn used in mats or rope.
Green coconuts, harvested after about six to 12 months on the palm, contain pliable white fibres. Brown fibre is instead 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 (dehusking). 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 process up to 2,000 coconuts per hour.
In 2009, researchers at CSIR's National Institute for Interdisciplinary Science and Technology in Thiruvananthapuram developed a biological process for the extraction of coir fibre from coconut husk without polluting the environment. The technology uses enzymes to separate the fibres by converting and solubilizing plant compounds to curb the pollution of waters caused by retting of husks.[17]
Bristle coir is the longest variety of coir fibre. It is manufactured from retted coconut husks through a process called defibering. The coir fibre thus extracted is then combed using steel combs to make the fibre clean and to remove short fibres. Bristle coir fibre is used as bristles in brushes for domestic and industrial applications.
Due to its superior absorption capabilities when compared to products made of clay, silica and diatomaceous earth-based absorbents, dry coconut coir pith is gaining popularity as an oil and fluid absorbent. Many other absorbents have to be mined, whereas coconut coir pith is a waste product in abundance in countries where coconut is a major agriculture product.
Coconut fiber (coir) is used as a construction material because the natural fibers are eco-friendly. Additionally, coconut fiber (CF) is resistant to thermal conductivity, is very tough, ductile, durable, renewable and inexpensive. It was observed in an experimental study that by partially replacing 2% of cement with CF, the compressive strength of the concrete is increased.[24] 2ff7e9595c
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