Mimosa tenuiflora TANNIN QUALITY FOR THE PRODUCTION OF TANNIN FORMALDEHYDE ADHESIVE

A jurema-preta ( Mimosa tenuiflora ), esp\ue9cie abundante no semi\ue1rido brasileiro, tem potencial para a produ\ue7\ue3o de taninos, havendo a necessidade de pesquisas que indiquem as melhores formas de aplica\ue7\ue3o dos mesmos. Este estudo objetivou avaliar a qualidade dos taninos da jurema-preta para a produ\ue7\ue3o de adesivo tanino formalde\ueddo com o per\uedodo de coleta da planta. Foram realizadas coletas de casca nos meses de agosto e dezembro de 2008 e em abril e agosto de 2009, na Fazenda Lameir\ue3o, Santa Terezinha, Para\uedba, sendo coletadas 10 plantas por per\uedodo, totalizando 40 plantas. As cascas foram retiradas do tronco e galhos de di\ue2metro de at\ue9 3,0 cm, mo\ueddas em moinho de facas e classificadas em peneiras e empregadas para a extra\ue7\ue3o de taninos, part\uedculas inferiores a 1,0 x 2,0 cm e superiores a 0,2 x 0,2 cm. Os extratos t\ue2nicos para a produ\ue7\ue3o de adesivos foram extra\ueddos em \ue1gua destilada em uma autoclave na temperatura de ebuli\ue7\ue3o da \ue1gua \ue0 press\ue3o atmosf\ue9rica, concentrados por evapora\ue7\ue3o ao ar livre e mantidos em estufa a 70 \ub1 3\ub0C, at\ue9 a completa evapora\ue7\ue3o da umidade. Foram avaliados o teor de s\uf3lidos totais, \uedndice de Stiasny e teor de taninos condensados nas cascas. Para produzir os adesivos, foi realizada a sulfita\ue7\ue3o \ue1cida dos taninos obtidos. Houve influ\ueancia do per\uedodo de coleta das plantas no teor de taninos condensados. Foi encontrado nos adesivos produzidos com os taninos de jurema-preta, valor de teor s\uf3lido semelhante aos da ac\ue1cianegra ( Acacia mearnsii ), n\ue3o havendo diferen\ue7a significativa entre os per\uedodos de coleta para o teor s\uf3lidos e tempo de gelatiniza\ue7\ue3o dos adesivos. Por\ue9m, o per\uedodo de coleta influenciou o pH e a viscosidade dos adesivos. Os adesivos produzidos tiveram viscosidade elevada, indicando a necessidade de pesquisas para a melhoria dos mesmos.Mimosa tenuiflora is an abundant species in the Brazilian semi-arid region which offers potential for the tannin production but need research indicating the best ways of its application. This study aimed to evaluate the quality of tannin from Mimosa tenuiflora for the formaldehyde tannin adhesive production with the plant collection period. The bark collections were carried out in the months of August and December of 2008 and in April and August of 2009, in Lameir\ue3o farm, in municipality of Santa Terezinha, Para\uedba state, Brazil, being collected 10 plants per period, totaling 40 plants. The barks were taken from the trunk and branches up to 3.0 cm in diameter, ground into mill knives and classified in sieves, having been employed for the extraction of tannins, particles less than 1.0 x 2.0 cm and superior than 0.2 x 0.2 cm. The extract tannic for the adhesives production was extracted in distilled water in an autoclave at boiling temperature of water at atmospheric pressure, concentrated by evaporation and kept in an oven at 70 \ub1 3 \ub0C until the complete evaporation of moisture, and was evaluated the total solid content, Stiasny\u2019s index and condensed tannin content in the bark by collection period. To produce the adhesives, an acid sulphitation of tannins was obtained. There was influence of period of collection of the plants in condensed tannin contents. It was found in adhesives produced with the tannins of Mimosa tenuiflora, solid content values, similar to those of Acacia mearnsii , no significant difference between collection periods for the solid content and gelatinization time of adhesives was obtained. However, the collection period influenced the pH and viscosity of adhesives. The adhesives produced showed high viscosity, indicating the need for research to improve the adhesives produced