Types of Biofibers

Cellulosic fibers, which are currently viewed as viable alternatives to synthetic fibers in the manufacture of NFRPs, have already established their place in the infrastmcture and commercial products market Currently, many types of natural fibers, derived from either wood and agricultural fibrous plants (such as flax, hemp, jute, and kenaf) or vegetable wastes (such as bagasse, rice husk, and grass), have already been investigated for use with plastics. Table 6.1 shows a list of biofibers and their sources [10] a more detailed discussion on natural fiber reinforcements can be found in Chapter 3 of this book. In general, biofibers can be considered... 

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. 

Incorporation of biofibers in biopol5miers results in biocomposites with improved properties. Because of huge abundance of data available on the properties of biocomposites, it will not be possible to cover them all. For this reason, we shall take one most widely used biopol5nner from each of the three classes of biopol5miers and discuss the properties of their biocomposites. The biopol5miers selected for this purpose are starch, PLA, and PHB. Table 10.4 presents a comparison of physical and mechanical properties of these three types of biopolymers with a commodity thermoplastic PP. It is evident that the density and mechanical properties of biopolymers are comparable to those of PP, although their low thermal stability is a matter of concern. 

Alkalization is the process of subjecting a biofiber to the action of a fairly concentrated aqueous solution of a strong base (alkali] so as to produce great swelling with resultant changes in the fiber structure, dimension, morphology, and mechanical properties. It depends on the type and concentration of the alkaline solution, its temperature, time of treatment, tension of the material as well as the additives used. Most of the non-cellulosic components... 

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