Bast fibers processing

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While some of the Mississippian textiles are of similar structure to the Middle Woodland textiles, others are very complex materials and are lace-like in appearance. Many of the materials from Etowah are preserved by mineralization, and display green-colored deposits on their surfaces. Bast fiber, rabbit hair, and feathers have been identified (2, 11). The textiles from these two sites selected for analysis are representative of the complexity of structure and fineness of yarns seen in the materials they provide evidence of the sophisticated technology of prehistoric people in all phases of fiber collection, processing, yarn spinning, fabric manufacture and, when present, coloration. 

The Comparative Plant Fiber Collection is a comparative collection of plant materials and the bast fibers they yield through different processing techniques (21, 22). The plants collected were typical of those used by prehistoric native Americans of eastern North America in the manufacture of fabrics, particularly those with fine yams. The CPFC contains representative fibers from 34 genera and species of plants that were collected in Ohio and Georgia in 1991 and 1992, with multiple stems gathered from each plant, and the fiber processed from the plant by four different methods ... 

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. 

The chemical properties of cellulose contribute to the qualities that make linen such an attractive fabric (i.e., its smoothness, strength, and water absorbency). Bast fibers, found in the phloem (a component of the plant s vascular system) are used to make linen. They contain thicker cell walls than most of the other plant tissues. In a chemical process called retting, bast fibers are harvested after the rest of the plant is decomposed by bacteria. Because of the large amount of cellulose within their cell walls, bast fibers can withstand the numerous corrosive chemical reactions of decomposition. 

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. 

Natural fibers can be classified as seed fibers (such as cotton), bast fibers (like flax, hemp, jute, kenaf, ramie), hard fibers (like sisal), fi-uit fibers (like coir), and wood fibers. The chemical composition and dimensions of some common agro-fibers are presented in Table 5.21. The origin of wood fibers can be sawmill chips, sawdust, wood flour or powder, cutter shavings, pulp or wood residues. As binders for these fibers, both thermosetting (like phenolic, epoxy, polyester) resins and thermosetting matrices [such as polyethylene (LDPE, HDPE), polypropylene (PP), poly(vinyl chloride) (PVC), polystyrene (PS)j can be used. Thermoplastic composites are, however, less expensive to process than thermosetting composites, in addition to their ability to be manufactured into complex shapes. 

Jute has also been used to make paper, although the entire plant is rarely used [64]. Pulp mills generally buy old jute sacks, cuttings, and waste wrapping material that are mainly bast fiber. Jute is usually pulped using either a chemical or by one of several chemimechanical processes. The Jute Technological Research Laboratory (JTRL) in Calcutta, India, has done... 

The bleaching processes used for bast fibers are usually milder, with longer treatment times than those used for cotton, to preserve the strand structure as much as possible. Details... 

Munder F., FtirU C., Hempel H., Processing of bast fiber plants for industrial application, in Natural Fibers, Biopolymers and Biocomposites, Eds. Mohanty A.K., Misra M. and Drzal L.T., CRC Press Taylor Francis Group, Boca Raton, 2005, pp. 109-140, Chapter 3. 

To facilitate and integrate research on bast fiber retting and subsequent processing, a pilot plant was established to quickly and effectively evaluate processes (Akin et al. 2005 Foulk et al. 2008a, 2009). The USDA Flax Fiber Pilot Plant (Flax-PP), the only research facility of this type in the US, is able to process and extract bast fibers from retted and unretted plant stalks using commercial-type equipment. 

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... 

Abstract A wide variety of natural fibers can be applied as reinforcement or fillers in composites. Bast fibers, such as fiax and hemp, have a long history of cultivation and use. They are characterized by low weight and excellent range of mechanical properties. The properties of bast fibers are influenced by conditions of cultivation, retting, and processing. Pretreatment and surface modification of bast fibers is conducted for optimization of the interfacial characteristics between fiber and matrix as well as improvement of their mechanical properties. Application of bast fibers as reinforcement to replace the glass fibers to composite manufacture brings positive environmental benefits. 

All parts of fibrous plant stem must be removed for proper fiber separation. Bast fiber extraction is usually conducted using special processes such as water and dew retting, degumming, or decortication, in which the separation of bundles craitaining elementary fibers joined together by pectin and calcium ions is also performed. Fiber content in the stem of fibrous plants is shown in Table 4.1. 

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