Fabrication of nano-cupric oxide in phenol–formaldehyde resin adhesive: synthesis, curing characteristics, and morphology

To explore the possibilities of reducing the costs of nano-copper oxide (CuO)-modified phenol–formaldehyde (PF) resin, PF resin synthesis and nano-CuO preparation utilizing different copper salts were carried out simultaneously in one system. The curing kinetics, morphology, as well as physical and mechanical properties of modified PF resins-bonded oriented strand boards (OSB) were evaluated. Nano-CuO showed a positive effect on the curing reaction of the PF resin, characterized by a significant decrease in the activation energy of the reaction. X-ray diffraction and transmission electron microscopy tests showed that the derived nano-CuO was in nano- and microscale. Four different types of crystal structure of the nano-CuO, varied according to their copper salts, were observed in scanning electron microscopy images. The water resistance and bonding strength of glued OSB prepared with these resin samples indicated that the influence of nano-CuO on the mechanical properties of the boards was positive. This system has the potential to be applied to the engineered wood-based composites manufacturing.