A Novel Bio‐Based Filler Extracted From Waste Cattle Hair and Its Application in PU Coatings—A Closed Loop Strategy for Solid Waste

ABSTRACT In the process of leather production, the hair‐preservation unhairing method plays a crucial role. In this research, waste cattle hair (WCH) obtained from the hair‐saving unhairing process in the leather industry was recovered. Then, the WCH was treated using the mechanical ball milling method to obtain the bio‐based filler (BF). The BF was subsequently incorporated into a solvent‐based polyurethane (PU) film applied to the surface of synthetic leather materials to enhance its permeability to air and water vapor. The effects of filler mass fraction, concentration, and temperature of the coagulation bath on the properties of the PU film were studied. The properties of the PU film were analyzed by FT‐IR, SEM, Universal Tensile Machine, Water contact angle measuring instrument, TG, DSC, DMA, etc. The experimental results indicated that the pore distribution in the PU film containing BF was more uniform, and its hydrophilicity and water vapor permeability were improved. As the BF content increased from 0% to 2%, while the water contact angle of the PU film decreased from 106.6° to 86.2°, the gas and the water vapor permeability increased by 6.6 mL/(cm 2 ·h) and 0.39 mg/(cm 2 ·h) compared with the control sample. TG, DSC, and DMA analysis showed that the glass transition temperature of the PU film with BF increased. The recycling of WCH achieves the circular economy.