Chitosan-Starch Films Reinforced with Natural Fibers

2 Chitosan-Starch Films Reinforced with Natural Fibers 

The development of new materials using natural fibers has become an area of great interest, mainly due to the importance of improved materials that can be used in everyday life. 

The plants that produce natural fibers are classified as primaiy and secondaiy depending on their utilization. Primary plants are those that are grown for their fiber content, whereas secondary plants are those in which the fibers are produced as a by-product There are six basic types of natural fibers obtained from plants. They are classified as follows bast fibers Oute flax, hemp, ramie, and kenaf), 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) (Faruk et al., 2012). 

In addition, natural fibers to reinforce composites also can have a non-plant source. For instance, keratin fibers obtained from wool or feathers. These are composed mainly by a fibrillar protein called keratin, which recently has been successfully used as reinforcement in synthetic pol5mieric matrix. Martinez-Hemandez and Velasco-Santos (2011) recently published a review with the most important results in feather keratin-reinforced composites. However, including this fiber in natural matrix is a new opportunity area, since there have been very few efforts in this regard. 

Recently, Flores-Hernandez et al. (2014) developed a green composite chitosan-starch as matrix and keratin biofibers as reinforcement. Keratin biofibers from feathers are non-abrasive, eco-friendly, biodegradable, renewable, and insoluble in organic solvents and also have good mechanical properties, low density, hydrophobic behavior, ability to dampen sound, warmth retention, and finally low cost (Meyers et al., 2008 Martinez-Hernandez and Velasco-Santos, 2011). Flores-Hernandez etal. (2014) developed the ecocomposites using three different kinds of keratin reinforcement short and long biofibers and rachis particles. These were added separately at different concentrations to the chitosan-starch matrix and the composites were processed by a casting/solvent evaporation method. 

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