THE INFLUENCE OF NANOCELLULOSE AND SILICON DIOXIDE ON THE MECHANICAL PROPERTIES OF THE CELL WALL WITH RELATION TO THE BOND INTERFACE BETWEEN WOOD AND UREA-FORMALDEHYDE RESIN

Urea-formaldehyde (UF) resin is used as an adhesive in the most wood-based composite plants in China. The quality of such composites is strongly affected by the mechanical properties of the cell wall in relation to the interface between UF resin and wood. This research investigates the mechanical properties of the cell wall in the bond interface of wood and UF resin with nanocellulose and silicon dioxide, and compares the mechanical properties of wood-adhesive interface cell walls to their gluing strength. The hardness and reduced modulus of the cell wall were investigated by means of nanoindentation. The test results show that there was a close relationship between the mechanical properties of the cell walls at the wood-adhesive interface and the percentage of nanocellulose or SiO2 in the UF. The shear strength of UF resin with nanofibrillated cellulose (NFC) or nano-SiO2 in bonded wood also gradually increased when the content of these two kinds of nanomaterials was increased from 0% to 2%.