Tannins of eucalyptus bark and its efficiency in wood glue.

Name: SABRINA BARROS SANTIAGO

Publication date: 06/07/2016
Advisor:

Name	Role
FABRICIO GOMES GONÇALVES	Advisor *
JUAREZ BENIGNO PAES	Co-advisor *
MARINA DONARIA CHAVES ARANTES	Co-advisor *

Examining board:

Name	Role
FABRICIO GOMES GONÇALVES	Advisor *
GRAZIELA BAPTISTA VIDAURRE	Internal Examiner *

Summary: The aim of this study was to evaluate the feasibility of using extracted tannins of eucalyptus bark with water and water under different concentrations of sodium carbonate and sodium sulphate as adhesive for wood. The eucalyptus bark were obtained in a wood processing company, and waste wood in a carpentry shop, both in the southern state of Espírito Santo. From the bark, total solids content and polyphenol content were determined using the Stiasny reaction. Reactive polyphenol content by the Ultra Violet Method – UV, pH, tannin and non-tannin levels of tannic extracts were also determined. For the chemical characterization of the bark and wood (density classified into three classes: low, medium and high) the extractives content, lignin, ash, holocelulose, pH and buffer capacity were determined. After obtaining tannic extracts, its properties were determined, with subsequent collage on wood. The adhesives were evaluated by the tensile shear test and failures percentage of wood glued joints. The results obtained showed that the sodium carbonate afforded greater extraction of tannins (8%) and sodium sulfate (4%) smaller quantities, both with good features, but not enough for use as adhesive for wood in its entirety (100%). Therefore, adding 10 to 20% of tannin in urea resin were used, and does not adversely affect the bonding of wood. The highest shear strength was found in high density wood class in for all studied adhesives. The highest values obtained for the failure percentage of wood glued joints occurred when using the most adhesives in low-density wood.

Keywords: Polyphenol, tannin extraction, natural adhesive, wood.

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