The effect of veneer-surface modification with fumed nanosilica on the selected properties of water-resistant plywood

The aim of the presented research was to investigate the effect of veneer modification with both 2% aqueous dispersion of fumed nanosilica and dispersion of fumed nanosilica containing additional 5% of wood fire retardant, on bonding quality and the flammability parameters of water-resistant plywood. The veneer modification was evaluated using SEM images. The bonding quality was determined through shear strength tests conducted post-aging procedures. Flammability tests were conducted using a mass loss calorimeter and the French method. Parameters such as heat release rate, average rate of heat release, mass loss, time to ignition, time of flameout, total heat release, burned surface area were determined to assess the fire resistance. The results showed that the modification of veneers with nano-SiO2 did not affect the bonding quality, however, the application of a dispersion containing a small amount of fire retardant resulted in a significant reduction in the shear strength. Significantly shorter ignition time was recorded for both modification methods, but at the same time, a reduction in a mass loss and an amount of heat released was also observed. The obtained results indicate the potential of veneer's surface modification with fumed silica to increase fire resistance of plywood with high bonding quality.