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Coir
0.35 usd/kg
Coir is a short, coarse fibre extracted from the shell of coconuts. Copra, milk and desiccated coconut are food products made from coconut, and coir fibre is a byproduct of this. 60% of coir comes from India, in particular Kerala, and one third from Sri Lanka.
The two types of fibre are white, extracted from unripe coconuts with thick walls made of cellulose, and brown from mature and ripe coconuts that are more lignin. While the white fibre is soft and fine, the brown mature fibre is very tough and salt water-resistant, with relatively high lignin content (>40%).
It makes up a large proportion of the seed, from the white edible flesh to the hard woody husk. The tradition process of extraction is labour intensive and time consuming – the husks are soaked in water for 12 months (retted), during which time anaerobic fermentation takes place, softening the fibres and allowing them to be separated. The fibres are hammered with mallets to release the individual strands, and then dried in the sun. Industrial manufacturing is much faster, using decorticating machines to extract the fibres after soaking for only 5 days or so.
Coir fibre (from kayar cord) from mature coconuts is a stiff hollow fibre also known as the golden fibre due to its light brown colour. It is hardy and used in floor mats, rope, compost, filters (aquariums), brush bristles and sacking. As well as being resistant to burning (not easily combustible), fungi and moth, one of its major advantages is that it is resistant to salt water – it has evolved to protect the nut when floating on seawater for months before washing up on a beach and growing into a new palm. It is used in geotextiles, to cover landscapes and provide erosion control, because it biodegrades slowly and so helps promote new vegetation growth.
Coir fibre is used as reinforcement in bio-based composites for automotive, household and construction materials. For example, it is combined with epoxy or polypropylene (PP) to make stiff, semi-structural panels for automotive interiors and panelling (it is lighter and less expensive than glass fibre); polylactic acid (PLA) to make biocomposite for stationary and single-use products (such as cutlery); latex natural rubber as matting, upholstery and mattresses (rubberised coir); and concrete for construction projects (fibre-reinforce concrete).
