Biodegradable natural fiber composites

Fiber reinforced composites, depending on the properties needed, can be fabricated in three different ways. Very short fibers can be used as filler, short fibers can be organized with random orientation and long fibers can be laid in one direction to form unidirectional composites. Short staple fibers may also be twisted together to form continuous yams to fabricate unidirectional composite laminates similar to those made using long fibers. Several unidirectional laminates may be combined by layering in different directions to form laminar composites. Yarns may also be woven or knitted into fabrics to form similar laminar composites. 

Most of the fibers and resins currently available on the market are derived from petroleum. There are two major problems associated with using petroleum as the feedstock for polymers. First, it is a non-renewable (non-sustainable) resource and at the current rate of consumption, by some estimates, it is expected to last for only 50-60 years [1]. Also, the current petroleum consumption rate is estimated to be 100,000 times the rate of natural generation rate [1]. Second, most fibers and resins made using petroleum are non-degradable. Although this is desirable in many applications from the durability point of view, at the end of their life, they are not easy to dispose of. Discarded 

There are plenty of examples in the literature where plant-based fibers have been used for reinforcing or filling non-degradable resins such as polypropylene (PP), polyethylene (PE), nylons, polyvinyl chloride (PVC), epoxies and polyurethanes (PU), etc. [6-15]. The bulk of plant-based fiber composites, however, are made using wood flour, a byproduct from saw mills, or wood fiber obtained from waste or used wood products, e.g. packaging pallets, old furniture, and construction wood scraps. These inexpensive 

Since these composites combine non-degradable resins with plant-based degradable fibers they can neither return to an industrial metabolism nor to a natural metabolism. Unfortunately, they cannot be food stock for either system. They can only be downcycled because of their property degradation during reprocessing or incinerated to recover the energy value. 

The following sections provide brief information regarding the plant-based fibers and describe some of the research efforts in developing green composites using plant-based fibers and soy protein-based resins. 

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M.Q. Zhang, M.Z. Rong, X. Lu. Fully biodegradable natural fiber composites from renewable resources all-plant fiber composites. Compos. Sci. Technol. 65, 2514-2525 (2005). 

Goda, K., Gomes, A., Asahi, T., and Yamane, T. (2002) Development of biodegradable natural fiber composites by press forming method. Proceedings of the International Workshop on Green Compo, Society of Material Science, )apan, pp. 8-11. 

Polymers reinforced with cellulose fibers have received much attention in recent years because of their low density, nonabrasive, combustible, nontoxic, low cost and biodegradable properties. Several authors have reviewed recent advances in the use of natural fibers in composites like flax [ 1 ], jute [2,3], straw [4], kenaf [5,6], coir [7-9], fique [10], among others. Natural fibers have been used to reinforce thermoplastics and thermosets polymers in automotive and aerospace applications [11]. The influence of surface treatments of natural fibers on interfadal characteristics was also studied [12-17], and Joshi et al. [18] compared the life-cycle environmental performance of natural fiber composites with glass fiber composites. In this study, natural fiber composites were found to be environmentally superior in most applications. 

Du Y, Wu T, Yan N, Kortschot MT, Famood R. Fabrication and characterization of fuUy biodegradable natural fiber-reinforced poly(lactic acid) composites. Compos PartB 2014 56 717-23. 

Natural fiber reinforced polymer composites have attracted the attention of the research community [88] and extended to almost all the fields. Much work is done in the application of natural fiber as reinforcement in polymer composite [114]. Natural fibers are an attractive research area because they are eco-friendly, inexpensive, abundant and renewable, lightweight, have low density, high toughness, high specific properties, biodegradability and non-abrasive to processing characteristics, and lack of residues upon incineration [120, 119]. Natural fiber composites such as hemp fiber-epoxy, flax fiber-polypropylene (PP), and china reed fiber-PP are particularly attractive in automotive applications because of lower eost and lower density. 

In the recent past considerable research and development have been expanded in natural fibers as reinforcement in thermoplastic resin matrix. These reinforced plastics serve as an inexpensive, biodegradable, renewable, and nontoxic alternative to glass or carbon fibers. The various advantages of natural fibers over man-made glass and carbon fibers are low cost, low density, competitive specific mechanical properties, reduced energy consumption and biodegradability. Natural fiber reinforced composites with thermoplastic matrices have successfully proven their qualities in... 

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