Introduction
Coco fiber manufacturing starts from the protective husk of the coconut. The matured coconut crop is de husked after harvesting. The individual fiber cells are narrow and hollow with thick walls made of cellulose, and each cell is about 1 mm long and 10–20 μm in diameter. The raw coco fibers show length varying from 15 to 35 cm and diameter from 50 to 300 μm. When they are immature and then become hardened and yellowed because a layer of lignin is deposited on their wall .
In the early stages of the coco fiber production process, the coconut husk is soaked in water for 6-7 months to soften it. Coir (lignin) should be removed to obtain fiber from the softened coconut husks. There are 03 methods used for this.
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- Traditional fiber extraction
- Mechanical extraction
- Green decortication and Microbial treatments
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Traditional coco fiber extraction
The traditional coco fiber manufacturing from the husks is a laborious and time-consuming process. After separating of the nut, the husks are processed by various retting techniques generally in ponds of brackish waters (for three to six months) or in backwaters or lagoons. This requires 10-12 months of anaerobic (bacterial) fermentation.
By retting, the husks are softened and can be decorticated and the fiber is extracted by beating, which is usually done by hand. After hackling, washing and drying (in the shade) the fibers are loosened manually and cleaned. The remaining residual pith – which was previously considered a waste problem – has recently found new profitable markets as a peat moss substitute for horticultural production.
Traditional practices of this kind yield the highest quality of (white) fiber for spinning and weaving. Retted fibers from green husks are the most suitable fibers for dyeing and bleaching. For the production of more coarse brown yarns shorter periods of retting may be applied. These find an increasing outlet in geo-textile applications.
Mechanical coco fiber extraction
Alternatively, mechanical processes using either de-fibering or decorticating equipment process the husks after only five days of immersion in water tanks. Crushing the husk in a breaker opens the fibers. By using revolving “drums” the coarse long fibers are separated from the short woody parts and the pith. The stronger fibers are washed, cleaned, dried, hackled and combed.
Green decortication and microbial treatments
New environmentally friendly methods for fiber production are of interest. These can be locally exploited on relative small-scale, and have the potential to produce a more constant quality of fibers. Using a bio-technological approach with specific microbial enzymes have reduced the retting time substantially to three to five days. High quality fiber production has been maintained.
Similar protocols can be developed to enhance the properties of the fibers in regard to surface properties such as smoothness and porosity. By using specific (microbial) lignolytic enzymes (laccase/phenoloxidase), the fiber surface can be bleached (or activated to react more easily with the dyes).
