Design and characterization of sustainable bio-composites from waste chicken feather keratin and thermoplastic polyurethane

A polyurethane-based polymer, and a sustainable, natural resource in the form of chicken feather (keratin) fibers were combined to form a bio-composite via solvent-casting-evaporation at 0, 10, 20, 30, 40, 50, 60, and 70%·w/w. The thermo-mechanical properties of the composites were assessed using thermogravimetry, dynamic mechanical analysis, and stress-strain measurements with hysteresis loops. The uniformity of the dispersion of the feather fiber in the polyurethane matrix was investigated via macro-photography. Scanning electron microscopy of fracture surfaces was used to verify that the adhesion between fiber and polymer was effective. A molecular modeling visualization predicted the existence of hydrogen bonding between fibers and polyurethane molecules and this result was supported by Fourier transform infrared analysis of the final composites. Addition of chicken feather fibers to the polyurethane matrix was found to decrease the glass transition temperature, recovery strain and mass loss of the composites, but increase the elastic modulus, storage modulus and char level. The results demonstrate that keratin derived from what is currently a waste product from the poultry industry (with significant economic and environmental disposal costs) can effectively and cheaply improve the thermo-mechanical properties of composite materials, with potentially large environmental benefits.