Preparation and characterization of biodegradable films from keratinous wastes of the leather industry

Abstract

With increasing demand for sustainable materials, keratin wastes have been regarded, in recent years, as renewable resources worthy of exploitation. Each year, the Portuguese leather industry discards a considerable amount of animal hair, which constitutes a troublesome waste product. In this study, in an attempt to find a potential utilization for this waste, the preparation of biodegradable films from bovine hair, by thermo-compression, was tested. Bovine hair formulations with 20, 30 and 40 wt % of plasticizer (glycerol, lactic acid) were pressed into films, at 147 kN and 120ºC or 160ºC for 4 minutes. The mechanical properties, colour, solubility and water sorption isotherms of the obtained films were assayed. All films were opaque and dark. Solubility was higher for films processed at higher temperature and with lactic acid as plasticizer. The Guggenheim-Anderson-de Boer (GAB) model gave a good fit to the experimental results for the moisture sorption isotherms. The stress at break, , and the Young's modulus, E, decreased and the strain at break, , increased with the addition of increasing amounts of plasticizer.