Curtimento de peles de Tambaqui (Colossoma macropomum) e Pirarara (Phractocephalus hemiolioptencs) com curtentes sintéticos e com curtentes naturais da Amazônia

Abstract

The hydric richness of Amazon region reveals a great arnount of ichtic species living in their waters. Amazonas state in 2005 produced 55.412,5ton of originating fiom fish of fiesh waterThe preparation of the leather starting fiam the residual skins of the filletage of fish by the fieezers represents an alternative source of income that can serve as raw material for production of artifacts. Studies accomplished in INPA, with several species of fish skins of Amazon demonstrated the feasibility of the transformation of these skins in leather. The conservation of the animal skin is need to remove some elements that compose the skin, that is possible through the use of organic dor inorganic substances. The purpose of this paper was the developping process of tanning of fish skins and to make comparing the mechanical resistance of the obtained leather. In the tannin extraction the barks of the species were collected hand-operated and placed in distilled water, resulting in a relationship waterhark of 25:l and heated to tlie ebullition yielding an aqueous extract of the material. Therefore afler the extraction, the sawdust was taken to the oven to 103 k 2C and it evaporates until reaching a constant weight, for the determination of the yield of extractive in hot water. The skins selected for study were of the species of Aamazon fishes: tambaqui (Colossoma macropomum) and pirarara (Phractocephalus hemioliopturus). The method to tan fish skins was the same developed for great animais with some modifications) and wasfollowed of several stages. For the determination of the resistance to shear and tension and strechting and progressive tearing was used was adopted method ABNT (NBR 11041) modified. Byrsonima sp. and Anacardium sp. species indicated the highest yield extractive total extractive in hot water being 69,6% and 62,6%, respectively, while Musa sp. presented the lowest concentration (42,2%). Tanning fish skins with extracted tannin of the regional plants showed results were not acceptable, however using the organic products (synthetic vegetable extracts) and the inorganic ones (chrome salt) used in the process, obtained satisfactory being in agreement with other skins of fish tanned. The resistance tests of the leathers in general are inside of the patterns of elasticity demanded by the technical specifications. The tambaqui leathers presented higher resistance when tanned with a module of elasticity of 55,64% with tannin and 34,64% for the tanning to the chrome. With regard to the progressive tearing all the characteristics (tear, maxirn forces and load force) were larger for the tanned skins with tannin. For the pirarara fish skins, the strechting was just fiom 79,8% and 51,5% to the tanning with chrome salt and natural tannin. Progressive tearing essays, as well as for the tension and strechting essays tfor he leathers in both tanning types presented high resistance and elasticity .values. The results found in this work for resistance are similar those found for other fish species, in accordance the literature on matter, although the products can influente in the resistance. In brief, is suggested the carrying out of new researches for seeking of the techniques of applied tanning and the accomplishment of the physical and mechanical properties in the leathers, allowing the obtaining of product of good quality for with market value for fish skins of the region.