Development of wood-products adhesives from mangrove bark

Abstract

Mangrove bark was extracted using either water, ethanol, acetone, or various binary mixtures of these, as solvent. With plywood panels as substrates, joints prepared with adhesives derived from these extracts were tested for strength properties. In terms of the quantity of extracts from mangrove bark, water was the most effective solvent, followed sequentially by ethanol and acetone. However, in terms of the tannin content of these extracts, the order of extraction effectiveness of these solvents was reversed. The use of solvent mixtures in tannin extraction did not produce an observable synergistic effect. The quantity of extract and its tannin content were dictated primarily by the predominant solvent in the binary mixture. The reactivity of mangrove bark extracts is influenced significantly by formaldehyde concentration, cure temperature, type, and pH of the adhesive medium. Adhesive joints of significant bond strength were obtained from mangrove tannin adhesives. Prolonged cure periods, particularly at elevated temperatures, have deleterious effects on the strength properties of these adhesive joints.