THE EFFECT OF HEAT ON WOOD ACIDITY IN PARTICLEBOARD PROCESS

In order to investigate the influence of processing variables such as particle drying temperature, press temperature and hardner consumption on wood acidity and bonding performance of UF resin, experimental boards were produced using beech wood particle, drying temperature varied at 80, 110 and 140°C, press temperature at 150, 165 and 180°C and hardner consumption at 1, 1.5 and 2% (based on solid content of UP resin). Eighty one sample boards were produced and tested. The results of physical and mechanical properties measurements were as follows: Modulus of rupture and modulus of elasticity of boards produced with particles dried at 80°C were higher than 110 and 140°C. Application of 2% hardener with increasing press temperature decreased MOR and MOE. Internal bonding of boards were measured and the results indicated that drying temperature had significantly effected the IB and boards produced  with particles dried at 80 and 140°C, produced highest IE and lowest IE was belong to 110°C. The effect of hardner consumption was statistically significant and the highest IB was belonging to 2% hardner consumption. The results of thickness swelling measurement after 2 hr. soaking in water indicated that T.S2 of boards produced with particles dried at 140°C were the lowest. The combined effect of press temperature and hardner consumption on T.S2 was statistically significant and at 2% hardner consumption with increasing press temperature, increased thickness swelling.