The Extraction of Keratin from Human Hair Waste for Copolymerization with Nitrile Butadiene Rubber

Abstract

Human hair contains a rich source of a fibrous protein called α-keratin. Due to keratin’s intrinsic ability to self-assemble and polymerize into porous, fibrous scaffolds and reproducible architecture, dimensionality, and porosity, its biomedical application has become widespread. However, the extraction of keratin from hair proves challenging and ineffective, hindered by its disulfide bonds. The purpose of this research is to explore a relatively simple procedure to extract keratin from hair waste and fuse it with NBR in hopes of enhancing its mechanical properties and improving its biodegradation. Keratin’s non-covalent bonds were broken using mechanical disruption by a grinder. Hair keratin is then extracted via solubilization by utilizing sodium chloride. The alkaline hydrolysis method, a simple, cheap, and time-affordable method, is explored with different concentrations of NaOH. Then, the recovered keratin from each solution is mixed with dissolved NBR (Nitrile Butadiene Rubber), a well-known rubber used for a variety of purposes, such as the construction of hoses, belts, sealing parts, oil seals, oil wells, and shoe soles. A series of tests on the mechanical properties of the keratin-filled NBR samples were then tested, such as tensile strength, elongation at break, hardness, and elasticity. 10g NaOH/100mL solution yielded the highest amount of keratin, with the addition of keratin from the same solution in NBR enhancing the mechanical properties the most, although only modest. Additionally, the inclusion of keratin in NBR improves its biodegradability.