Fiber vegetable

Fibers for commercial and domestic use are broadly classified as natural or synthetic. The natural fibers are vegetable, animal, or mineral ia origin. Vegetable fibers, as the name implies, are derived from plants. The principal chemical component ia plants is cellulose, and therefore they are also referred to as ceUulosic fibers. The fibers are usually bound by a natural phenoHc polymer, lignin, which also is frequentiy present ia the cell wall of the fiber thus vegetable fibers are also often referred to as lignocellulosic fibers, except for cotton which does not contain lignin. 

Vegetable fibers are classified according to their source ia plants as follows (/) the bast or stem fibers, which form the fibrous bundles ia the inner bark (phloem or bast) of the plant stems, are often referred to as soft fibers for textile use (2) the leaf fibers, which mn lengthwise through the leaves of monocotyledonous plants, are also referred to as hard fibers and (J) the seed-hair fibers, the source of cotton (qv), are the most important vegetable fiber. There are over 250,000 species of higher plants however, only a very limited number of species have been exploited for commercial uses (less than 0.1%). The commercially important fibers are given ia Table 1 (1,2). 

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. 

Fiber Dimensions. Except for the seed-hair fibers, the vegetable fibers of bast or leaf origins are multiceUed (Fig. 1) and are used as strands ... 

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. 

Urena and Abutilon. These are less important vegetable fibers of a jute-like nature. Urena lobata (Cadillo) of the mallow family (Malvaceae) is a perennial that grows in Zaire and Brazil to a height of 4—5 m with stems 10—18 mm in diameter. Because of a lignified base, the stems are cut 20 cm above the ground. The plants are defoflated in the field and retted similarly to jute and kenaf. The retted material is stripped and washed and, in some cases. 

Table 8. Value and Unit Priee of U.S. Vegetable Fibers Imported ...

Fiber Analysis. Paper may be composed of one or several types of fibers, eg, animal, vegetable, mineral, and synthetic (see Eibers). Paper is generally composed of woody vegetable fibers obtained from coniferous (softwood) and deciduous (hardwood) trees. QuaUtative and quantitative methods have been developed to determine the fibrous constituents in a sheet of paper (see TAPPI T401). However, the proliferation in the number and types of pulping processes used have made the analysis of paper a much more complex problem. Comprehensive reviews of the methods are given in References 20 and 23. 

The largest use of zinc chloride in the United States is in wood preservation, fluxes, and batteries (see Batteries). Zinc chloride solution dissolves vegetable fiber and is widely used in mercerizing cotton (qv), swelling fibers, as a mordant in dyeing, parchmentizing paper, etc (see Fibers, vegetable ... 

Vegetable fiber, glue binder 212 Resists oil and water to 212 F. 

Processing aid Petroleum based Synthetic low PCA content oil, vegetable oil Casing Synthetic fiber Vegetable fiber... 

Usage of vegetable fiber in place of synthetic fiber as a casing material... 

Paper and board are composed of cellulose obtained by the mechanical or semi-chemical treatment of vegetable fibers (pulp) derived from various sources like wood, hemp, cotton, etc. In some cases waste and regenerated paper is used. 

Cellulose, the most abundant biological substance on earth, is the basic and major component of most plant tissues it is the substance that makes up the walls of vegetable cells and therefore the framework of vegetable fibers. The molecules of cellulose are long, linear polysaccharides, made up of many (several hundreds and even over 1000) aligned glucose monomers... 

The main constituent of all fibers of vegetable origin (see Table 88) is, almost exclusively, cellulose, a polymeric carbohydrate (see Textbox 53). Vegetable fibers are resistant to alkalies and to most organic acids but are destroyed by strong mineral acids. 

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