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Content: The application of split leather is an important issue in leather industry as most of them was not properly treated and wasted. In this study the application of choline chloride (ChCl), urea (U) and corresponding deep eutectic solvents (DES) on the modification of thermal stability and mechanical strength of mink split leather was investigated. TGA and DSC results indicated DES treatment enhanced thermal stability of split leather, and ChCl treatment reduced the stability. While, U treatment provided a kinetic inhibition during the thermal-decomposition. In terms of the mechanical strength, both ChCl and U treatment reduced burst intensity and extended height. While, after DES treatment the burst intensity and extended height increased significantly. In terms of the dosage, 7% DES provided best performance. Results mentioned above illustrated that DES formed by simply mixing ChCl and U provided strong interaction with fiber, enhanced the crosslinks. A hypothesis of [Ch(Urea)]+[Cl(Urea)]- type structure was proposed, as it enabled DES forming strong hydrogen bonds with functional groups on leather fiber, enhancing the crosslinks and therefore improving the thermal stability and mechanical strength. The DES treatment on leather fibers improved their overall performance and thereby broaden their applications. Take-Away: 1. DES obtained by mixing ChCl and urea presented very different effect in leather treatment, as the thermal stability and physical strength of leather improved significantly after the DES treatment. 2. A hypothesis of [Ch(Urea)]+[Cl(Urea)]- type structure was proposed, illustrating a formation of strong hydrogen bonds between DES and functional groups on leather fiber. This enhances the crosslinks and therefore improves the thermal and mechanical strength of leather. |
