Some of Physical and Mechanical Properties of Particleboard Panels bonded with Phenol- Lignin- Glyoxal Resin

Investigation of the properties of particleboard panels bonded with a phenol-lignin-glyoxal (PLG) resin as a new type of wood adhesive was the aim of this research work. Thus, various contents of soda bagasse lignin (20, 30 and 40 wt%) as a substitute of part of the phenol were used to synthesize PLG resins, coupled with glyoxal as a nontoxic aldehyde. The resins prepared were then used to bond particleboard panels. The physicochemical properties of the synthesized resins and physical and mechanical properties of the particleboard panels bonded with the PLG resins were measured. The thermal properties of the resins were also analyzed by Differential Scanning Calorimetry (DSC). Finally, the properties of the resins and of the panels bonded with them were compared with those of a control PF resin and the relevant EN standards. The results showed that PLG resins, especially at the higher percentages of lignin, had slower gel time and lower viscosity compared to the control PF resin. DSC analysis also indicated that curing of a PLG resin with 30 wt% lignin substitution needs a higher temperature than for a PF resin. Although the panels bonded with PLG resins presented weaker mechanical properties and lower dimensional stability compared to those bonded with PF resins their properties still satisfy the requirements of the relevant standards specifications. The results of this work indicated that panels bending and internal bond strengths, as well as their dimensional stability, decrease with an increasing percentage of the lignin content from 20% to 40% by weight, while the flexural modulus increases.