Production of Phenol-urea-formaldehyde Resin (PUF) and Investigation of its Resistive Properties in Particleboard

In this study, phenol was partially substituted with urea to reduce the production cost of phenol formaldehyde resin (PF), and a new resin phenol-urea-formaldehyde (PUF) was synthesized. Different formulations of resin PUF with different molar ratios were made using different methods. The structure of the formulated resins and their coagulation behavior were evaluated with infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC), respectively. FT-IR and DSC analysis indicated the best results for the synthesized PUFB3 which was made from phenol, urea, and formaldehyde with a molar ratio of 1: 0.5: 1.7, respectively, and exhibited a similar methylene structure with PF resin. Then, the formulated resins were applied to produce particleboard. Mechanical properties of the produced particleboards were determined and compared with those of ones which were prepared with PF resin as the control treatment. The findings demonstrated that the substitution of urea increased the dry internal bonding strength and modulus elasticity but reduced the internal binding strength of the produced particleboards following a two-hour immersion into boiling water. The findings revealed that the mechanical properties of the particleboards produced with PUFB3 resin were comparable with the control treatment, and the formulation of phenol, urea, and formaldehyde with the molar ratio of 1: 0.5: 1.7 was selected as the optimum treatment for outdoor condition and under load. In addition, the particleboards produced with PUFD1 resin which was formulated of phenol, urea and formaldehyde with the molar ratio of 1: 0.5: 2.5 exhibited standard properties for application in outdoor conditions without load.