Investigation on the influence of urea addition to urea-formaldehyde adhesive on physical and mechanical properties of poplar particleboard

Effect of increasing urea additions to urea-formaldehyde adhesive on physical and mechanical properties of poplar wood particleboard was investigated. Four levels of urea (0, 4.1, 8.2, 16% based on the solid content of adhesive) and two hot pressing times (170 and 180° C) were investigated. Boards with the density of 0.63 gr. /cm3 and 10% adhesive were prepared. Mechanical properties including modulus of rupture (MOR), internal bond (IB) and physical properties including water absorption and thickness swelling were measured. Results showed that the urea addition to urea formaldehyde adhesive improved the mechanical strengths of the board and reduced the water absorption and thickness swelling. Also, the impact of press temperature on mechanical and physical properties of boards was significant and the boards produced applying 170° C press temperature was superior.