Uniformity and Softness of Kenaf Fibers for Textile Products

To incorporate kenaf fibers into textiles, it is important to establish uniformity of fibers extracted from the base to the tip of the plant. Bast fiber quality depends on both physical (crystallinity, crystallite size, and orientation) and chemical (lignin, gum, and hemicellulose) properties. Therefore, the first objective is to determine fiber uniformity, evaluating the effect of processing on tenacity, elongation, crystallinity, crystallite size, and chemical composition of fibers extracted from base to tip of the stalk. Second, to make fibers spinnable, the effect of various softeners is evaluated. Decorticated kenaf stems (variety E41) have been retted chemically and bacterially to extract fibers. Fiber bundle strength ranges from 22-30 g/tex. Gum content decreases from 20-10% with the initial chemical processing; later degumming does not reduce gum levels. Initial gum removal increases crystallinity by 3-5% and crystallite size by 20-25%. Physical and chemical properties of kenaf fibers are uniform along the whole length of the native stalks. Alkali treatment with 1% NaOH is not sufficient to impart noticeable stretch. Enzyme and degumming treatments weaken the fibers significantly (30-45%). The commercial softener makes fibers too sticky, and they stick to the carding equipment. Bending rigidity and hysteresis (recovery after repeated bending) do not significantly improve for the softened fibers. Degummed fibers are the strongest. most pliable, with least hysteresis and lowest residual gum content, and are spinnable.