Surface modification of eco-friendly particleboard made from sorghum bagasse and citric acid sucrose adhesive

Abstract

Eco-friendly particleboard made from sweet sorghum bagasse bonded with citric acid and sucrose was developed and met the minimum requirement of JIS standard. The surface roughness of particleboard which is important for coating with thin overlays, however did not measure yet. Therefore, the effect of particle size composition in surface modification of particleboard on the physical and mechanical properties of the panel was investigated. Sorghum bagasse has been used as raw materials in the manufacturing of three-layer particleboard. The composition of coarse particle (core layer) and fine particle (face and back layers) in the fabrication of particleboard was varied into four compositions such as A (0 (face): 100 (core): 0 (back), B (12.75:75:12.75), C (25:50:25), D (37.5:25:37.5)). Particleboard was bonded with 20 wt% of citric acid-sucrose (CAS) adhesive based on dry weight of particle and hot-pressing at 15 MPa and 200°C for 10 minutes. Dimension and target density of particleboards were 30 x 30 x 0.9 and 0.8 g/cm3, respectively. The physical and mechanical properties of the particleboard were evaluated according to JIS A 5908-2003. The Moisture Content (MC), Thickness Swelling (TS), Water Absorbtion (WA), Internal Bonding (IB) strength, Modulus of Elasticity (MOE) and Modulus of Rupture (MOR) values of the particleboard satisfied the requirements for the type 8 JIS A 5908-2003 standard. The particleboard made of composition C had lowest value of surface roughness. The addition of fine particle ratio on the surface layer lowered the WA and TS of the particleboard and slightly increased the IB strength. Further, the MOE and MOR of the particleboard was not affected by increasing fine particles on the surface layer. This study suggests that particle size composition remarkably affects the physical and internal bonding strength of particleboard, while it has less interference to the mechanical properties.