Abstract

Plant-derived vegetable fibers are classified according to their source in plants as bast, leaf, or seed-hair. The fibers in bast and leaf plants are integral to the plant structure, providing strength and support. The principal chemical component of vegetable fibers is cellulose, with varying amounts of lignin and hemicelluloses also usually present; thus the fibers are also referred to as cellulosic or lignocellulosic. Vegetable fibers are usually stiffer but less tough than synthetic fibers. The fibers are grown throughout the world but mostly in tropical and subtropical climates in developing countries. The principal bast fibers are flax, jute, and hemp which are utilized primarily for fabrics (linen-flax, hessian-jute), bags, ropes, in newer biobased composites and as a source of papermaking fibers, principally cigarette papers. The primary leaf fibers are abaca and sisal, which have uses similar to bast fibers, except fabrics are not produced from the leaf fibers. Cotton, coir, and kapok are the principal seed-hair fibers, with cotton by far the most important commercial vegetable fiber. Bast fibers are obtained from the plant, after harvest, by water retting (rotting) in ponds or streams. The leaf fibers are obtained by crushing and scraping followed by washing. Vegetable fibers are generally graded according to color, luster, cleanliness, strength, fineness, and uniformity. The world market for vegetable fibers has dropped dramatically in recent years because of periods of economic recession and synthetic fiber replacements.