Determination of optimum formulation of tusam (Pinus merkusii) tannin bark with resorcinol and formaldehyde

Abstract

Adhesive is the one of main components that used for producing composite wood. The quality of the adhesive can affect the strength of the composite wood. However, adhesives which commonly used are synthetic adhesives that contain a lot of formaldehyde emissions and have negative impact on our health. To reduce its use, we need an alternative adhesive from natural raw materials. Tannin is a phenolic compound has been widely studied that can be used as a bio adhesive for wood composites. The main source of tannin for adhesive is derived from bark. One type of wood bark that contains tannins is tusam wood bark. Tannins have a high reactivity against formaldehyde. This study aims to determinate the optimum formula of tannin which is copolymerized with resorcinol and formaldehyde. Tannin is obtained by extracting wood bark with hot water. The optimum formula of tannins and resorcinol (TR) result is determined by the stiasny numbers, while the optimum formula of tannins and formaldehyde (TF) are determined by identification of solid content. The addition of resorcinol affects the percentage of stiasny number, the greater the formula of resorcinol added, the higher value of stiasny number, wherein the reactivity of tannin to formaldehyde increases. The addition of formaldehyde also affects the results of tannin formaldehyde solid content, the more addition of formaldehyde, the percentage of solid content decreases.