Tannin-based adhesive from Ceriops decandra (Griff.) bark for the production of particleboard

Abstract

This study presents the extraction of tannins from the bark of a common mangrove species named goran (Ceriops Decandra (Griff.) Ding Hou) and the technical evaluation of the tannin-based adhesive for the production of particleboard. Extraction of tannins was performed by hot water extraction method at 80 ± 5 °C temperature for 3 h. Chemical analysis of the bark extract was carried out to determine the percentage of total phenols and total condensed tannins. Tannin-based adhesive was prepared by adding 0, 25, 50, 75 and 100% (w/w) tannin with the commercial grade urea–formaldehyde (UF) resin. Solid content, viscosity and pH of the adhesive solution was measured. Particleboards were manufactured from Albizia saman (Jacq.) wood particles and 8% adhesive (w/w basis). Physical and mechanical properties of the particleboards were evaluated according to the ASTM D-1037 standard. From the results, it was observed that the adhesive formulation containing 100% tannin showed the highest viscosity (512 cP), solid content (57.3%) and the lowest pH value (4.2) followed by adhesive formulation containing 75% tannin. The highest modulus of elasticity (MOE) and modulus of rupture (MOR) (948 and 18.4 MPa, respectively) were found for particleboards fabricated with 100% tannin-based adhesive. Though, the results indicate that tannin in combination with UF, even in pure form, is technically feasible to use as an adhesive for the production of particleboard. However, need to reduce the thickness swelling and improve MOE of the particleboards as these properties were not satisfactory for medium density particleboard grade according to ANSI standard. Therefore, further research on different ratios of tannin and UF/phenol formaldehyde (PF) and high temperature pressing of particleboard is recommended.