QUALIDADE DOS TANINOS DE JUREMA-PRETA (Mimosa tenuiflora) PARA A PRODUÇÃO DE ADESIVO TANINO FORMALDEÍDO Mimosa tenuiflora

Abstract

ABSTRACTMimosa tenuiflorais an abundant species in the Brazilian semi-arid region which offers potential for thetannin production but need research indicating the best ways of its application. This study aimed to evaluatethe quality of tannin fromMimosa tenuiflorafor the formaldehyde tannin adhesive production with theplant collection period. The bark collections were carried out in the months of August and December of2008 and in April and August of 2009, in Lameirão farm, in municipality of Santa Terezinha, Paraíba state, Brazil, being collected 10 plants per period, totaling 40 plants. The barks were taken from the trunk andbranches up to 3.0 cm in diameter, ground into mill knives and classified in sieves, having been employedfor the extraction of tannins, particles less than 1.0 x 2.0 cm and superior than 0.2 x 0.2 cm. The extracttannic for the adhesives production was extracted in distilled water in an autoclave at boiling temperatureof water at atmospheric pressure, concentrated by evaporation and kept in an oven at 70 ± 3 °C until thecomplete evaporation of moisture, and was evaluated the total solid content, Stiasny’s index and condensedtannin content in the bark by collection period. To produce the adhesives, an acid sulphitation of tanninswas obtained. There was influence of period of collection of the plants in condensed tannin contents. Itwas found in adhesives produced with the tannins ofMimosa tenuiflora, solid content values, similar tothose ofAcacia mearnsii, no significant difference between collection periods for the solid content andgelatinization time of adhesives was obtained. However, the collection period influenced the pH andviscosity of adhesives. The adhesives produced showed high viscosity, indicating the need for research toimprove the adhesives produced.