Win–Win Approach Toward Chrome-Free and Chrome-Less Tanning with Waterborne Epoxy Polymers: A Sustainable Way To Curb the Use of Chrome

Leather, a natural biomaterial sourced from animal skins and hides, is characterized by its intricate three-dimensional collagen fiber network. In this study, we present an innovative approach to stabilize goat skins using chrome-free and chrome-less tanning processes using epoxy polymers to comprehend surface active properties. Comprehensive structural and chemical analyses of the synthesized epoxy polymers were conducted employing Fourier-transform infrared spectroscopy (FT-IR), nuclear magnetic resonance, and gel permeation chromatography (GPC) for molecular weight determination along with particle size analysis in a water emulsion (1–2%). The surface tension was carried out for the surface activity of the polymers. Epoxy tanning yielded leather with a notable shrinkage temperature (Ts) of 80 ± 2 °C, when combined with chrome tanning (3%), bringing Ts to 101 °C, similar to that of conventionally processed leather. The combined tanning achieved a significantly higher thickening rate of 108% and higher softness than chrome-tanned leathers. Comprehensive analyses of physical attributes, including tensile strength (26 N mm2), tear resistance (78 N mm), elongation (48%), and shrinkage temperatures, were conducted. Field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDX) were employed to visualize the elemental composition and infer information on the splitting of collagen fibers. This approach of surface active tanning agent in leather processing technology results in improved leather properties with a reduced environmental footprint.