Classification of Plant Fibers

There are several different classifications in terms of plant fibers. While the classification of Nishino [59] includes seven groups as bast (soft) fibers (flax, hemp, jute), leaf (hard) fibers (sisal, abaca, pineapple, etc.), stem fibers (bamboo, banana stalk, corn stalk), fruit fibers (coconut), seed fibers (cotton, baobab, kapok), straw fibers (rice, wheat, corn), and others (seaweeds, palm), that of Faruk et al. [3] has six groups bast fibers (jute, flax, hemp), leaf fibers (abaca, sisal and pineapple), seed fibers (coir, cotton and kapok), core fibers (kenaf, hemp and jute), grass and reed fibers (wheat, corn and rice) and all other types (wood and roots). 

The traditional plant fiber classification groups are bast, leaf and seed/fruit fibers, other than wood fibers. 

The fibers which are found in the stem or stalk of bast plants and mechanically support the plants are called bast fibers [60]. Bast fibers have drawn quite an amount of interest in terms of composite reinforcement ptuposes [14] due to their superior mechanical properties [9]. 

Leaf fibers have lower elasticity moduli and higher elongation, and better toughness, and consequently, higher impact resistance than bast fibers. This is caused by their greater microfibril angle [56]. 

Other than cotton, seed fibers generally exhibit the lowest densities and the highest microfibril angle among plant fibers. They have high failure elongation and low elasticity modulus [61]. 

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