Decortication, machine

Lanka. The fruits are broken by hand or machine, and the fiber extracted from the broken husks from which the coconut has been removed for copra. The husks are retted ia rivers, and the fiber separated by hand beating with sticks or by a decortication machine. The fibers are washed, dried, and hackled, and used ia upholstery, cordage, fabrics, mats, and bmshes. 

Large sisal decortication machines (Stork, Robey, and Corona) are also used to extract the fiber. The machines are similar in their operation. In each case, an endless conveyor feeds 200-300 leaves/min into the machine (see Figure 8.3b). They are first crushed by a pair of... 

The machines are quite similar in operation to sisal-decorticating machines. Continuing interest in improving the effectiveness of the process is manifest in the studies of Savinovskii [151], and Lavitskii and Ipatov [86] improvements sought relate to productivity, quality of scutched fiber, and prevention of the loss of long fiber. 

Figure 11.3 Decorticating machine used for mechanical fiber extraction. (From A. V. R. Prasad, K. M. Rao, G. Ragavmrrasulu, Indian Journal of Fibre and Textile Research, 2009 [30]. With permission from Indian Journal of Fibre and Textile Research).

Before straw is processed and fibres extracted, it has to be retted. In Asia, Africa and Latin America kenaf is still retted in ponds. However, this process is labour intensive and leads to serious contamination of waterways [47,49], therefore, like many other bast fibre yielding crops, kenaf can be dew-retted. The second stage of processing involves a series of decortication machines that break the stem and separate core and bast fibres [50]. 

The plant is harvested by hand sickle and, after defoUation, is stripped and scraped by hand or machine decorticated. Because of the high gum (xylan and araban) content of up to 35%, retting is not possible. The fibers are separated chemically by boiling in an alkaline solution in open vats or under pressure, then washed, bleached with hypochlorite, neutralized, oiled to facUitate spinning, and dried. 

Henequen. Agavefourcroydes grows ia Mexico where it was first cultivated by the Mayans ia the Yucatan (Yucatan Sisal). The plant produces for 20—30 years. The lower bottom leaves, which are up to 2 m long and 10—15 cm wide, are cut, machine decorticated, and cleaned. Henequen fibers are white to yellowish red and are inferior to sisal ia strength, cleanliness, texture, and length, the other grading criteria. Henequen is grown for local use ia Cuba (Cuban Sisal) and El Salvador. Twiae, small ropes, coarse mgs, and sacks are made commercially from henequen. 

After cutting, the spike at the tip of the leaf is removed and leaves are bundled for transportation to the decortication site. This must be carried out as soon as possible since the cut leaves soon deteriorate if left exposed to the sun and decortication will become difficult. Sisal plantations in India yield about 2.5 ton dry fiber per hectare per year, with an annual net profit of Rs. 45,000 per ha. The fiber is usually obtained from sisal leaves by decortication in a machine called Raspador. The lustrous strands, usually creamy white, average from 80 to 120 cm in length and 0.2-0.5 mm in diameter. 

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