Leaf fibers

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). 

The long leaf fibers contribute strength to the leaves of certain nonwoody, monocotyledonous plants. They extend longitudinally the hiU length of the leaf and are buried in tissues of a parenchymatous nature. The fibers found nearest the leaf surface are the strongest. The fibers are separated from the pulp tissue by scraping because there is Htde bonding between fiber and pulp this operation is called decortication. Leaf fiber strands are also multiceUed in stmcture. 

Fig. 4. Cross sections (500x) of leaf fibers (a), abaca and (b), sisal.

Sisal. The tme sisal fiber Fora Agave sisalana is the most important of the leaf fibers ia terms of quahty and commercial use. Originating ia the tropical western hemisphere, sisal has beea transplanted to East Africa, Indonesia, and the Philippines. It is named after the port ia the Yucatan from which it was first exported. 

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. 

Leaf fibers (sisal, pineapple, screw pine)... 

Leaf Fibers Abaca Musa textilis plants... 

The principal bast and leaf fibers are produced in yields of 2-5%. with some exceptions such as flax (I Slid and kapok 11 7%). on a green plant basis. Vegetable fiber production on lire world market has dropped 25-3.VJ1 since 1970 because of periods of economic recession and synthetic fiber replacements. Imports of vegetable fibers have dropped 70-90% since... 

Vegetable fibers are classified according to the part of the plant that they come from. The four groupings are seed-hair fibers, leaf fibers, bast fibers, and miscellaneous fibers. 

Leaf fibers come from the leaves of monocotyledo-nous plants. They are primarily used for cordage. 

Rept. 5, A Report on the Leaf Fibers of the United States, Detailing Results of Recent Investigations Relating to Florida Sisal Hemp, the False Sisal Hemp Plant of Florida, and Other Fiber-Producing Agaves Bowstring Hemp, Pineapple Fiber, New Zealand Flax, and Bear Grass, 1893. 

Various reports are present in the literature on the usage of cellulose fibers in the preparation of composites. Cellulose fibers like banana, sisal, oil palm, jute, pine apple leaf fiber were found to have a very good reinforcing effect on polymer matrices [38 2]. The mechanical properties and water absorption were found to be dependent on the amount of micro-fibrils. 

There are many kinds of natnral fibers, snch as bast fibers (flax, hemp, jute, kenaf, ramie, nettle, and mesta), leaf fibers (sisal, heneqnen, pineapple, abaca, oil palm, and screw pine), seed fibers (cotton), frnit fibers (coconnt hnsk, or coir), and stalk fibers (straw of varions kinds). They are not nsed for commercial WPG, primarily on economical reasons (except maybe Procell, see Table 1.1). Most of these fibers have fonnd applications in established indnstries, snch as textile indnstry (cotton, flax, jnte, ramie, hemp, and sisal) and paper indnstry (straw). 

Loading nose, 226, 232, 233, 236, 238, 239, 241, 242, 245, 253, 256, 265, 274 Long alkyl chain alkoxysilanes, 172 Long cellulose fiber, 79, 92, 98 Long natural fiber, 110 Abaca, 110 Bast fibers, 110 Cost of, no Cotton, 110 Flax, no Fruit fibers, 110 Hemp, no Henequen, 110 Jute, no Kenaf, 110 Leaf fibers, 110 Mesta, no Nettle, no Pineapple, 110 Ramie, 110 Seed fibers, 110 Sisal, no Stalk fibers, 110... 

For the secondary base fibers, the cell dimensions show little variation between plant species, but the number of spiral turns per unit length of cell averages only about four per millimeter, appreciably less than for the leaf fibers. 

The long bast or leaf fibers can be formed into flexible fiber mats, which can be made by physical entanglement, nonwoven needling, or thermoplastic fiber melt matrix technologies. 

Bast or leaf fiber can also be combined in an inorganic matrix. Such composites are dimensionally and thermally stable, and they can be used as substitutes for asbestos composites. Inorganic bonded bast fiber composites can also be made with variable densities that can be used for structural applications. 

A widely accepted classification of fibers is based on their location in the plant. Accordingly, the three principal categories are seed fibers, bast fibers, and leaf fibers. Fibers that do not belong to one of these three categories are classified as miscellaneous fibers. 

Such an approach to fiber classification appears to be systematic and objective. Unfortunately, plants do not always follow the pattern of roots, trunk, leaves, seed, or fruit. There are anomalies. For example, the banana-like plants, yielding abaca, do not have the woody trunk conventionally associated with other plants. Instead, its stem consists of layers of thick, crescentshaped (in cross section) sheaths wrapped around each other they reduce to spindly growths that unfurl from the stem and become the thick central stems of fronds (see Section 8.2.1). Botanically, the sheath-frond system is called a leaf consequently, the fiber extracted from the sheath is classified as leaf fiber. On the other hand, sisal or henequen fibers come from the swordlike leaves of their respective plants. Bagasse (from sugarcane) fiber, used for paper or fiberboard, comes from the stem, which is neither a leaf nor a woody trunk. Thus, the classification of fibers as seed, bast, leaf, or miscellaneous fibers is somewhat arbitrary. 

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