Starch Modified With Chitosan and Reinforced With Feather Keratin Materials Produced by Extrusion Process: An Alternative to Starch Polymers

Starch (potato), chitosan, and feather keratin are used for processing biodegradable films produced by extrusion. The morphology of the films is examined with a scanning electron microscope and showed the excellent dispersion of keratin. The dispersion is the result of compatibility between the polysaccharides and proteins, as well as the proper operation of the extrusion process. Water solubility of the starch‐chitosan films decreased with an increase of keratin materials. The storage modulus increased up to 137% for the composites with unmodified ground quill, and by 192% for composites with modified ground quill. In a tensile test, the composites with unmodified and modified quill reached outstanding increments up to 8160 and 7250% in elastic modulus, respectively, compared to the matrix. They also reached up to 3800% and 3150% in maximum strength, respectively, compared to the matrix. The lysozyme test showed relevant changes in the degradability rate, because the weight loss of the films at 3 weeks decreased from 53% for starch‐chitosan matrix and up to 34% for composites with 5 wt% of modified quill. The results corroborated that chicken feather materials can be useful for the development of a manufacturing process for starch composites, and the decomposition of starch‐chitosan composites can be controlled depending on the content and type of keratin. Three natural materials processed by extrusion successfully produce green composites. The biodegradable composites are made from potato starch modified with chitosan and reinforced with keratin obtained from by‐products of chicken feathers. The results show that the composites could be an important alternative to diversify and improve several properties for the starch films, based on natural reinforcements.