The effect of drying temperatures and tannin-adhesive types on bending properties and shear strength of glued Eucalyptus pellita board

Abstract

Eucalyptus pellita is usually harvested at young age for pulp and paper production. Therefore, it’s wood quality needs to be improved when it is used for construction. One of which is through its conversion into laminated products. Nevertheless, several factors are assumed to influence the final quality of laminated products, i.e pre-drying temperatures used to prepare the samples and the adhesives types used. This paper aims to investigate the effect of both factors on the bending properties and shear strength of glued Eucalyptus pellita boards. The Pellita boards were exposed to 2 drying temperatures (50°C and 60°C) and further laminated by using 2 tannin-based adhesives (made from the mahogany and oil palm bark extracts). The results showed the modulus of elasticity (MOE) and modulus of rupture (MOR) of the glued boards with mahogany-tannin adhesives were, respectively, 33,333.15-39,160.15 kg/cm2 and 214.30-640.77 kg/cm2 higher than the boards laminated with the oil palm wood tannin adhesives. Nevertheless, the oil palm tannin adhesives improved the shear strength of laminated Pellita, approximately 15.06-16.45 kg/cm2 higher than the boards laminated with mahogany-tannin adhesives. A further statistical test showed the tannin-types used for adhesives, and not the drying temperatures, that significantly affected the investigated mechanical properties of glued Pellita boards.