Bast fiber production

Screened kenaf Pelleted kenaf core Fines core powder 

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Bast fiber crops are a group of plants that can produce natural cellulose fibers from plant stem skin. In history, cultivation of bast fiber crops is the oldest method to produce natural fibers for meeting clothing needs and other daily necessaries. The most important bast fiber crops are ramie, flax, hemp, jute, and kenaf, based on their production capacity and consumption quantity. To date, the production of bast fiber crops still primarily aims at the textile market. Facing fierce competition from synthetic fibers that have increased productivity and a steadily expanded end-use market, the world capacity of bast fiber production continues to decline. Currently, the production volume of the major bast fibers in the world is about 4.8 million metric tons, equivalent to 14% of the global production of manufactured fibers (Fibersource, 2002). 

Kenaf and Roselle. These closely related bast fibers are derived from Hibiscus cannibinus and H sabdariffa (mallow family, Malvaceae), respectively. The fibers have other local names. Kenaf is grown for production in the People s Repubflc of China, Egypt, and regions of the former USSR roseUe is produced in India and Thailand. Plantation-grown kenaf is capable of growing from seedlings to 5 m at maturity in five months. It is reported to yield about 6—10 tons of dry matter per acre, nine times the yield of wood (13). 

Fibers (see Fibers, survey) used in textile production can have a wide variety of origins plants, ie, ceUulosic fibers (see Fibers, cellulose esters) animals, ie, protein fibers (see Wool) and, in the twentieth century, synthetic polymers. Depending on the part of the plant, the ceUulosic fibers can be classified as seed fibers, eg, cotton (qv), kapok bast fibers, eg, linen from flax, hemp, jute and leaf fibers, eg, agave. Protein fibers include wool and hair fibers from a large variety of mammals, eg, sheep, goats, camels, rabbits, etc, and the cocoon material of insect larvae (sUk). Real sUk is derived from the cocoon of the silkworm, Bombjx mori and for a long time was only produced in China, from which it was traded widely as a highly valuable material. 

Potential resources of xylans are by-products produced in forestry and the pulp and paper industries (forest chips, wood meal and shavings), where GX and AGX comprise 25-35% of the biomass as well as annual crops (straw, stalks, husk, hulls, bran, etc.), which consist of 25-50% AX, AGX, GAX, and CHX [4]. New results were reported for xylans isolated from flax fiber [16,68], abaca fiber [69], wheat straw [70,71], sugar beet pulp [21,72], sugarcane bagasse [73], rice straw [74], wheat bran [35,75], and jute bast fiber [18]. Recently, about 39% hemicelluloses were extracted from vetiver grasses [76]. 

Walser et al. [65] have published a LCA study using inventory data for polyester (PET) textile production. The authors also noticed that the data in the Ecoinvent database [66] on cotton and bast fibers do not specify the yam size, which has an important influence on energy use. 

The principal bast and leaf fibers are produced in yields of 2-5%. with some exceptions such as flax (I Slid and kapok 11 7%). on a green plant basis. Vegetable fiber production on lire world market has dropped 25-3.VJ1 since 1970 because of periods of economic recession and synthetic fiber replacements. Imports of vegetable fibers have dropped 70-90% since... 

The bast is prepared by retting, but the end product is not separated down to individual fibers. After processing, the bast is left in its original form, in long bundles that are usually brown from the tannins present in these plants. The bast fibers are from 4 to 7 feet long and large, with a diameter of 20—25 mm. 

The outer surface of the earspools from Tunacunnhee Mounds C and E and the reverse side of the breastplate display pseudomorphs that have shapes characteristic of bast fibers (Figure 7). Typical of these fibers, the pseudomorphs occur in bundles of irregular size which are used as units in fabric production. The fibers are longer than staple and exhibit little of the twisting required for short fibers to produce a usable yam. The fiber bundles of the bast group can be used with little processing in making fabrics. 

Evidently, the idea was there but the material was lacking then to perform successfully the process of fiber spinning. But when Henri Braconnot in 1832 and Christian Friedrich Schoenbein in 1846 discovered how to make cellulose nitrate, the time for the "spark" had arrived. British Patent 283, issued in 1855, disclosed the treating of bast fibers from mulberry twigs with nitric acid, dissolving the product in a mixture of alcohol and ether together with rubber, and from this viscous mass drawing fibers with a steel needle after these fibers solidified in air, they were wound on a spool. 

Jute is produced from plants of the genus Corchorus, which includes about 100 species. It is one of the cheapest natural fibers and is currently the bast fiber with the highest production volume. The fibers are extracted from the ribbon of the stem. Among all natural fibers, jute fibers are easily available in fabric and fiber... 

Kenaf is now being grown in several countries where the bast fiber is used for geotextiles and the pith is going into sorbents for oil spill clean up and animal litter. The production of pulp and paper from kenaf is growing, but it is only used for limited types of papers at present. The utilization of the whole plant of both jute and kenaf is under consideration for structural and nonstructural composites. Automotive interior door panels are now produced in Germany and the United States out of jute and kenaf bast fiber in combination with thermoplastics. 

Coloring matter, which in bast fiber, is located within the cortical cells, some of which remain attached to fiber bundles after scutching. It consists of chlorophyll, xantho-phyll, carotene, as well as their alteration products [188] they are associated with complex compounds of the tannin type. Another source of coloring matter is in the cambium cells this is usually connected with proteinic materials containing aromatic groups [41,42,57,93,108]. 

Fibrous plants can be classified from their purpose point of view. In this classification system, bast fibers are classified into group of fibrous plants cultivated just for fiber production. The second group of the system contains plants grown for other goods, for example, fruits - coconut production, and fibers constitutes only a by-product of the plant - coir (Pickering 2008). Another classification system indicates that most of the technically important bast fibers are obtained not only from plants cultivated in agriculture, such as flax, hemp, or ramie, but also from wild plants, such as nettle. 

Another strong aspect of vegetable fiber application in the industry is their ecological character with possibility of carbon dioxide reduction from the atmosphere during the fibrous plants cultivation processes. Use of bast fibers ensures biodegradability of the end product, if natural polymer, e.g., PLA is applied as a matrix. 

Basically, kenaf has two distinctive stem regions the outer part, or so-called bast, constitutes around 34% of the weight of the stem and the inner, woody core is about 66%. The long bast fibers are usually used to produce paper, protective packaging, and composite boards and are also used in textile industries. On the other hand, the short fibers are used to manufacture products like animal bedding and horticultural mixtures [25]. 

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