ABSTRACT
The inherent advantages of natural fibres, such as abundant presence, cheap processing, ease biodegradability and high strength, make them extensively useful for various applications such as aerospace, automobile and infrastructure. Although natural fibres are obtained from various sources such as plants, animals and minerals, plant fibres are used in large extent for making composites mainly due to their inherent characteristics and abundant availability. Cellulose, hemicelluloses, lignin, pectin, wax and other impurities are the main composition of plant fibres. Cellulose consists of repeating units of D-anhydro glucose, with each unit comprising three hydroxyl groups.1 Cellulose microfibrils embedded in the lignin matrix governs the strength, stiffness and stability of the fibres. The orientation of cellulose microfibrils to the fibre axis determines the stiffness of fibres. The fibres having spiral orientation shows ductile nature, and those with parallel orientation are rigid and inflexible. Moreover, they possess more tensile strength.2,3 Some of the desirable properties of natural fibres are higher cellulose content, low microfibrillar angle, smaller fibre diameter and longer fibre.4 Natural fibres are extracted from various parts of plants such as roots, seed, stem, fruits and leaves. Among the plant fibres, bast fibres commonly show the highest degree of polymerization.5 Due to lower density, bast fibres offer specific strength comparable with glass fibres. Bast fibres alone accounts for nearly 4 million metric tons of global production annually. The tensile strength of bast fibres depends upon their diameter and location in the stems.6 This is mainly due to the
variation of fibre size along its longitudinal axis. High tensile strength is possessed by the bast fibres obtained from the mid region of the stem.7 Although lignocellulosic fibres offer several advantages, they suffer from major drawbacks such as poor moisture resistance, poor adhesion with matrix and low processing temperatures.
