Tambaqui (Colossoma Macropomum) Leather Tanning A Study on the Influence of Skin Morphology on the Physical-Mechanical Properties of Leather

Abstract

The fish production chain presents losses of up to 35%, generating a large amount of waste. Using these residues to produce valueadded materials boost fish production towards a sustainable path. The use of fish skin to obtain leather is increasingly attracting the market for fashion and luxury products. Besides considered an exotic material with a unique design, fish leather also has good mechanical properties. Due to the morphology of fish skin, different mechanical responses can be observed, depending on the leather cutting direction. However, there are no specific technical standards for sampling this material. In this scenario, 45 Tambaqui skins were tanned with chromium associated with oxazolidine, and the mechanical properties of the leather were evaluated in four cutting directions: parallel, perpendicular, dorsal-ventral and ventral-dorsal, all concerning the cephalocaudal line of the fish. Skin and leather micrographs revealed layers of parallel collagen fiber bundles distributed in superimposed layers oriented obliquely to the preceding one. Insertions of collagen fibers perpendicular to the leather surface were also observed, joining the deeper layers to the superficial layers. Tensile strength (TS) and elongation (E) results indicated statistical differences, with higher TS results for the perpendicular cut and greater elongation for the parallel cut. The tear strength was higher for the ventral-dorsal cut, statistically differing from the parallel cut. The data indicate that the cutting direction of the specimen can influence the physical-mechanical behavior of the leather, reinforcing the importance of standardization for the qualitative evaluation of fish leather.