Bast, fibers

Flax is an annual plant native to the region extending from the Mediterranean to India. Flax fiber is a soft, flexible, and lustrous fiber extracted from the bast or skin of the stem of the flax plant. It has about 80% cellulose, 13% hemiceUulose, 

Ramie is a bast fiber obtained from the perennial herbaceous plant, Boehmeria nivea. It is mainly grown in China, India, Japan, Korea, and Philippines. Ramie plants are one of the fast-growing plants and can be harvested within an interval of a few months. Three crops of this plant can be harvested every year. Sisal is a hard fiber extracted from the leaves of the sisal plant Agave sisalana). The length of sisal fiber is between 1.0 and 1.5 m and the diameter is about 100-300 tm. 

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Fig. 1. Typical longitudinal section of bast fiber showing very long fiber strands composed of many ultimate fibers (see Table 3 for dimensions).

World markets for vegetable fibers have been steadily declining in recent years, mainly as a result of substitution with synthetic materials. Jute has traditionally been one of the principal bast fibers (toimage basis) sold on the world market however, the precipitous decline in jute exports by India (Fig. 2) indicate the decreasing market demand for this fiber that is vitally important to the economies of India (West Bengal), Bangladesh, and Pakistan. 

Among the bast textile fibers, the density is close to 1.5 g/cm, or that of cellulose itself, and they are denser than polyester, as shown iu Table 5. Moisture regain (absorbency) is highest iu jute at 14%, whereas that of polyester is below 1%. The bast fibers are typically low iu elongation and recovery from stretch. Ramie fiber has a particularly high fiber length/width ratio. 

Table 5. Textile-Associated Properties of Bast Fibers Compared to Polyester ...

The microfibrils iu vegetable fibers are spiral and parallel to one another iu the cell wall. The spiral angles iu flax, hemp, ramie, and other bast fibers are lower than cotton, which accounts for the low extensibiUty of bast fibers. 

Retting. The removal of the bast fibers from bark and woody stem parts is promoted by a biological treatment called retting (rotting). This is an enzymatic or bacterial action on the pectinous matter of the stem. After retting, the bundles are dried iu fields. Retting may be carried out iu several ways. 

Fig. 3. Cross sections (500x) of bast fibers (a), fiax (b), hemp (c), jute (d), kenaf and (e), ramie.

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). 

Abaca. The abaca fiber is obtained from the leaves of the banana-like plant (same genus) Musa textilis (banana family, Musaceae). The fiber is also called Manila hemp from the port of its first shipment, although it has no relationship with hemp, a bast fiber. The mature plant has 12—20 stalks growing from its rhizome root system the stalks are 2.6—6.7 m tall and 10—20 cm thick at the base. The stalk has leaf sheaths that expand iato leaves 1—2.5 m long, 10—20 cm wide, and 10 mm thick at the center the fibers are ia the outermost layer. The plant produces a crop after five years, and 2—4 stalks can be harvested about every six months. 

Phormium. The Phormium tenax plant yields a long, light-colored, hard fiber also known as New Zealand hemp or flax, although it has none of the bast fiber characteristics. The plant is a perennial of the Agavaceae with leaves up to 4 m long and 10 cm wide. The fibers are recovered by mechanical decortication. 

Leaf fibers Bast fibers Seed, fmit, and other... 

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. 

Basidiomycetes, reproduction in, 26 452 Basil leaf, 23 164 Basin-type solar still, 26 91 Basket centrifuge, 11 389-390 conical, 11 391 Bast fiber plants, 11 594 Bast fibers, 11 285, 288, 289 as cellulose source, 5 363, 367 mechanical properties of, 11 290-291 processing of, 11 291-295 uses of, ll 299t, 300... 

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