Biofiber physical properties

Singha, A. S., Thakur, V. K. (2009). Chemical resistance, mechanical and physical properties of biofibers-based polymer composites,... 

Diffusion and swelling studies of biofiber-reinforced rubber composites are very important as they provide information about its interface and the service performance in liquid environment. On absorption of liquid, the composite undergoes a diffusion process, which involves transfer of Hquid to its interior. Hence, the material swells as a whole, which leads to gradual deterioration in its physical and mechanical properties and subsequent premature failure. Several factors such as chemical structure and composition of the rubber compound, solvent, test piece size and shape, rubber-liquid ratio, temperature, time, presence of fillers affect the swelling behavior of elastomers. 

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. 

Starch is one of the most widely used biopolymer in biocomposites because of its low cost and versatility. A plasticizer like glycol is sometimes used to make it suitable for processing. It is also blended with other polymers like aliphatic polyesters to improve its physical and mechanical properties. Biocomposites based on starch matrices show improved properties, which are comparable to E-glass/epoxy composites. Tensile, flexural, impact, and creep properties of these biocomposites are significantly better than those of neat starch. Various biofiber surface treatments have been shown to improve the properties of starch-based biocomposites. 

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