Plant fiber

Plant fibers can be distinguished between seed fibers (fibers are connected to the seed), bast fibers (fibers that stabilize the stem), and hard fibers (fibers that reinforce the leaves). 

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Plant-fiber identification is described in TAPPI T8 and TIO. In order to identify synthetic fibers, it usually is necessary to conduct solubihty and physical properties tests in addition to light microscopy observations. Systematic sampling is required to obtain quantitative information on sample composition. Because different types of pulps contain varying numbers of fibers per unit weight, it is necessary to multiply the total number of each kind of fiber by a relative weight factor, thereby the weight percentage that each fiber type contributes to the sample can be deterrnined. 

The fundamental goal in the production and appHcation of composite materials is to achieve a performance from the composite that is not available from the separate constituents or from other materials. The concept of improved performance is broad and includes increased strength or reinforcement of one material by the addition of another material. This is the well-known purpose in the alloying of metals and in the incorporation of chopped straw into clay for bricks by the ancient Egyptians and plant fibers into pottery by the Incas and Mayans. These ancient productions of composite materials consisted of reinforcing britde materials with fibrous substances. In both cases the mechanics of the reinforcement was such as to reduce and control the production of cracks in the brittle material during fabrication or drying (2). 

Gespenstf n. specter, ghost, phantom. Gesperr(e), n. locking device, catch, ratchet, gespieen, p.p. (of speien) spat vomited. Gespinst, n. spun yarn spun goods thread (textile) fabric web cocoon, -faser, /. textile fiber, -pflanze,/. textile plant fiber plant. 

In general, natural fibers are subdivided as to their origin, coming from plants, animals, or minerals (Fig. 2). Plant fibers usually are used as reinforcement in plastics. The plant fibers may be hairs, fiber sheafs of dicotylic plants, or vessel sheafs of monocotylic plants (bast and hard fibers). 

Presently, the demand for plant fibers for technical applications can be partially met (Table 1). 

Table 1 Production of Plant Fibers in Comparison with Glass Fibers (1993) [60]...

Climatic conditions, age, and the digestion process influence not only the structure of fibers but also the chemical composition. Mean values of components of plant fibers are shown in Table 4. With the exception of cotton, the components of natural fibers are cellulose, hemi-cellu-lose, lignin, pectin, waxes, and water-soluble substances. 

Cellulose is the essential component of all plant fibers. It is an isotactic jS-1,4-polyacetal of cellubiose. The basic... 

The filaments of all plant fibers consist of several cells. These cells form crystalline microfibrils (cellulose), which are connected together into a complete layer by amorphous lignin and hemi-cellulose. Multiple layers stick together to form multiple layer composites, filaments. A single cell is subdivided into several concentric layers, one primary and three secondary layers. Figure 5 shows a jute cell. The cell walls differ in their composition and in the orientation of the cellulose microfibrils whereby the characteristic values change from one natural fiber to another. 

The angle of the fibrils and the content of cellulose determine the properties of the plant fibers. The Hearle et al. s model [19] considers only these two structure parameters. For the description of stiffness, solely, the St layers were considered because the properties of these fibers were decisively dominated by the amount of these layers. 

Nevertheless, the diagram of the characteristic values of plant fibers as dependent on structure parameters... 

The mechanical and physical properties of plant fibers are also influenced by the following structure parameters [17,21] ... 

Table 8 Structure Parameters of Diverse Plant Fibers [20]...

Table 8 also shows that the different plant fibers vary in the geometry of their cells. 

When used as substitutes for asbestos fibers, plant fibers and manmade cellulose fibers show comparable characteristic values in a cement matrix, but at lower costs. As with plastic composites, these values are essentially dependent on the properties of the fiber and the adhesion between fiber and matrix. Distinctly higher values for strength and. stiffness of the composites can be achieved by a chemical modification of the fiber surface (acrylic and polystyrene treatment [74]), usually produced by the Hatschek-process 75-77J. Tests by Coutts et al. [76] and Coutts [77,78] on wood fiber cement (soft-, and hardwood fibers) show that already at a fiber content of 8-10 wt%, a maximum of strengthening is achieved (Fig. 22). 

Mort AJ, Komalavilas P, Rorrer GL, Lamport DTA (1989). in Modern Methods of Plant Analysis Vol 10 Plant fibers, Linskens HF, Jackson JF eds Springer,... 

Muhlethaler, K. Electron Micrographs of Plant Fibers. Biochem. bio-physica Acta 3, 15 (1949). 

Enzymes from these organisms find numerous applications beyond PCR. Certain ones can modify plant fibers or break down proteins or fats. Heat-stable enzymes with these digestive properties are very attractive to the food processing industry. Properly controlled, their action can make prepared foods more palatable, and they can be employed where ordinary enzymes fail. In food processing, all operations must be carried out under sterile conditions. Frequently, the easiest way to maintain sterility is to keep the... 

For monitoring the extent of polysaccharide hydrolysis, l.c. methods that sepeu ate and analyze the non-fermentable oligosaccharides (d.p. 3-30) derived from cellulose, hemicellulose, and pectins are useful, and have already been described (see Section III,l,c). For determination of the monosaccharide composition of completely hydrolyzed, plant polysaccharides, l.c. is especially useful and has been applied to the compositional analysis of hydrolyzed plant fiber,wood pulps,plant cell-walls,and cotton fibers.In these representative examples, the major sugars of interest, namely, glucose, xylose, galactose, arabinose, and mannose, have traditionally been difficult to resolve by l.c. The separa-... 

Hemp rope, once widely used, has largely been replaced by iiylon cord. The flexibility and mechanical strength of hemp, a nettle plant fiber, also characterize nylon synthetic and several other inorganic fibers in common use. 

These assemblies of more simple structures to form more complex structures are also found in the plant world. Thus, plant fibers often contain various cellulose-intense layers that are not placed on top of one another, but rather at some angle to one another resulting in increased strength and flexibility for the fiber. 

Plant fibers such as cotton, abaca, agave, flax, hemp, kapok, jute, kenaf, and ramie are still in use but even cotton is no longer king. ... 

Hycar Trade name for Buna-N elastomer, jute Plant fiber used for making burlap. 

Watters, K., and P. Blaisdell. Reduction of glycemic and lipid levels in DB/ DB diabetic mice by psyllium plant fiber. Diabetes 1989 38(12) 1528-1533. 

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