Physico-chemical surface modification of the natural leather using gliding arc discharge: An in-depth analysis of improving surface and mechanical properties

Abstract

Leather, a widely used material in various industries, presents challenges in terms of dye uptake, hydrophilicity, and environmental concerns associated with chemical wet processing. In this context, non-thermal plasma technology offers a promising alternative for leather surface modification. In this study, the gliding arc, with air and water vapor plasmas, was used for the surface modification of natural leather for the first time. The influence of the treatment time and also the plasma gas chemistry on the surface chemical bonding, surface morphology, wettability, water absorption time and absorption capacity, color, and mechanical properties of the leather were investigated. The results showed that in the water vapor gliding arc discharge, the produced active oxygen and hydroxyl species can effectively react with the functional groups and break the relatively weak hydrocarbon CH bonds in the chemical composition of the natural leather. SEM images showed increased pore depth and diameter on the leather surface after air and water vapor plasma treatment with mean diameters of 76 μm and 92 μm, respectively. The tensile stress-strain curves illustrated that despite small cracks were created on the plasma treated samples, the elongation at break (ultimate strain) increased from 83.7 % to 88.5 % and 91.8 % for the samples treated with the air and the water vapor plasmas for 5 min, respectively. The water contact angle decreased from 96° to 55° and 48° after only 5-second treatment with the air and the water vapor plasmas, respectively. The same trend was also observed for the water absorption time and the absorption capacity of the treated samples. Also, the color analysis showed that the color change in the plasma treated samples was not detected by the unaided eye. It was also found that water vapor plasma has a better influence on the physico-chemical properties of the leather.