Bast fiber crops

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). 

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Specific gravity of dry CNP is about 1.57—1.59 g/cm tapped density can be 0.25—0.30 g/cm and bulk density 0.1—0.2 g/cm. The nanoparticles isolated from cotton cellulose, bacterial cellulose, and tunicate are usually chemically pure, while CNP from herbs, shmbs, bast fibers, crops, wood pulps, and some other sources may contain residual xylan and lignin. 

Bast fiber crops have a similar biological stem structure. They are typically composed of a bark layer, a bast layer and a stem core. The bark layer is called cuticle, a thin skin to form a protective stem surface and to hold bast fiber bundles. The bast layer includes a primary fiber layer where bast fibers can be extracted. The stem core usually consists of woody tissue called xylem and pith. Figure 12.2 shows the cross-sectional view of sunn hemp stem. The height of bast fiber crops varies depending on crop species. Overall, it is in the range of 60 to 600cm (Krishnan et al, 2000 Sahnon-Minotte and Franck, 2000 Sponner et al, 2000 Kozlowski et al, 2000). 

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. 

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]. 

At similar hydrolysis conditions, dimensions of the CNP depend on the origin of cellulose feedstock. In general, CNP derived from terrestrial plants (herbs, shrubs, crops, wood, bast fibers, cotton, etc.) have smaller sizes compared to those derived from other sources (tunicate, algae, and bacterial cellulose) this is in agreement with the lateral size of elementary crystallites (Habibi et al., 2010 Hanley et al., 1992 loelovich, 2014b Li and Ragauskas, 2011). 

Foulk J, Chao W, Akin D, Dodd R, Layton P (2006) Analysis of flax and cotton fiber fabric blends and reeycled polyethylene composites. J Polym Environ 14(1) 15-25 Foulk J, Dodd R, McAlister D, Chun D, Akin D, Morrison H (2007) Flax-cotton fiber blends miniature spinning, gin processing, and dust potential. Ind Crops Prod 25(1) 8-16 Foulk J, Akin D, Dodd R (2008a) Processability of flax plants into functional bast fibers. Compos Interf 15(2-3) 147-168... 

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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