The application of tannin extract from Anogeissus leiocarpus plant as wood adhesives

Abstract

This work reports the extraction and application of tannins as wood- adhesives from Anogeissus leiocarpus plant using water, acetone or a mixture of these as solvent. In terms of the quantity of extracts from polyphenolic extract of Anogeissus leiocarpus bark, water was the most effective solvent, followed sequentially by acetone and solvent mixture (90% acetone and 10% water). The use of solvent mixture in tannin extraction yielded high tannin content. The poly condensation reaction of Anogeissus leiocarpus bark extract is influenced significantly by amount of formaldehyde (9.0 ml), tannin (2.5 g), glycerol (0.6 ml), cure temperature 80^OC, types and pH 7.5 of the adhesive medium. Adhesive joint of significant bond strength were obtained from Anogeissus leiocarpus tannin adhesive. Prolonged cure periods particularly at elevated temperature have adverse effect on the strength properties of these joints, especially with wood- panels as substrates. Joint prepared with adhesive derived from these extracts were tested for strength properties.

Keywords: Anogeissus leiocarpus, tannin, polycondensation, Formaldehyde, cure temperature.