Annual Biofibers

On the basis of their life cycle, biofibers are divided into two types annual biofibers and perennial biofibers. Further, these biofibers are divided into different categories such as plant-based, animal-based, and mineral-based biofibers, depending upon their origin. Most plant fibers are composed of celluloses, hemicelluloses, lignins, pectins, and waxes, whereas animal fibers consist of proteins, for example, hair, silk, and wool. Plant fibers include stem fibers, leaf fibers, seeds, fruit wood, cereal crops, and other grass fibers. 

Nonwood fibers are annual fibers obtained from various monocotyledonous and dicotyledonous plants. Nonwood fibers include straw, grass, bast, leaf, and fruit fibers. During 1996-1997, world paper consumption was about 300 million tons 

obtained after the removal of grain and chaff from the dry stalks of cereal plants, is an agricultural by-product. Straw has various applications such as fuel, animal feed, bedding for livestock like horses, packaging and decoration material, and constraction materials. About half of the yield of cereal crops such as barley, oats, rice, rye, and wheat is straw. Straws are the main agricultural waste materials and by-products of agricultural plants and are rich resources of biofibers. Its wide utilization in different fields draws the attention of researchers to make useful industrial products from such agriculture by-products [19-23]. 

Straw has a more complicated constitution than wood. Straw contains a relatively large number of cell elements. It contains fiber, vessel elements, the parenchyma cells, and epidermic cells, having high amount of ash and silica. The epidermic cells form the outermost surface cells, which are covered by a very thin layer of wax. This surface layer reduces the moisture absorbance of straw. Wheat straw has higher cellulose, ash, and silica content as compared to that of wood. The wax content of straw is higher than that of wood. Rice straw has been found to possess higher wax content [24]. 

Wheat straw is one of the most important agricultural residues. It is available worldwide and is annual renewable source of biofiber. Only a very small part of wheat straw has been used as feedstock and energy production whereas most of it remains unused. During the past 20 years, the potential of wheat straw for papermaking and composite preparation along with other applications has been explored [25, 26]. 

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Biofibers have received much attention as reinforcements for composites due to many advantages such as annually renewable, sustainable, low cost, high specific... 

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