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Mimosa tenuiflora (Willd.) Poir. (MT) is an underutilized plant specie since its wood is mostly used for energy production. Nonetheless, the bark from this forest plant has a high amount of tannins and other valuable compounds. Tannins have high worldwide importance and, because of that, there is an increasing number of researches on biorefinery systems aiming at maximizing their exploitation. The present study evaluated tannins extracted from the MT bark and their use for producing wood adhesives. Three types of powdered tannins were extracted using different solvents: a pure aqueous solution, a 5% sodium hydroxide (NaOH) aqueous solution, and a 5% sodium bisulfite (NaHSO3) aqueous solution. Distilled water, wheat flour, and formaldehyde were also used as a solvent, a glue extender, and a catalyst, respectively. These adhesives were applied for bonding pine wood joints and their shear strengths were determined. All the MT-based adhesives showed high viscosities and, yielded glue lines with similar shear strengths and similar shear deformations if compared to each other. That tannin-based glue incorporated with the tannin extracted using NaOH or NaHSO3 stood out and yielded similar bonding performances if compared to a commercial adhesive applied as a positive control. [ABSTRACT FROM AUTHOR]

Among the methods tested to reduce the leaching of boron compounds in wood, it can be highlighted their combination with vegetable tannins. It is attributed the natural durability of some species of wood to vegetable tannins, pointing to their potentiality as natural wood preservatives. This research evaluated the efficiency of condensed tannins from bark of Mimosa tenuiflora extract with distilled water, compared to another extract added of sodium sulfite. It also evaluated the efficiency of sulfited tannin extracts, combined or not with boric acid in order to improve the resistance of Ceiba pentandra against the xylophagous termite Nasutitermes corniger by feeding test. Tannic extract obtained by adding sodium sulfite to distilled water revealed better yield compared to condensed tannin extraction. In general, impregnation of wood with tannin extract presented the same behavior as compared to application of boric acid, with best results observed when both them were simultaneously used. However, after applied to wood, tannin extracted was leachable and it did not favor the boric acid leaching. Despite the potential use of tannic extract against the xylophagous termite, additional studies are required for a best evaluation. [ABSTRACT FROM AUTHOR]

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