The impact of nanoparticles and moisture content on bonding strength of urea formaldehyde resin adhesive

Abstract

Wood and wood products have been used in different environmental conditions. Moisture content (MC) and relative humidity (RH) are key parameters for these conditions and bonding strength. Nanotechnology has paved the way to more durable adhesives. An experimental study was conducted to examine the effects of various nanoparticles and moisture content on bonding strength of urea formaldehyde (UF) resin adhesive. In this study, nanosilicon dioxide (SiO2) and titanium dioxide (TiO2) were blended with UF. Nanoparticle reinforced adhesives were processed at different nano fi llers concentrations (0.5 % and 1 %) and each adhesive was tested at the moisture content of 0 %, 12 %, 18 % and 25 %. According to the results of bonding strength tests, contained nano-SiO2 adhesives showed better bonding strengths as compared to the control (pure UF) and contained nano- TiO2 adhesives. The highest bonding strength has been determined at 12 % wood moisture in all specimens. Increasing the moisture content has decreased bonding strength of all samples including control samples. This study showed that nano (SiO2 and TiO2) particles have improved the bonding strength of pure UF. Besides, the addition of nano-SiO2 and nano-TiO2 changed the physicochemical properties of UF adhesive by XRD test. The novelty of this study was to demonstrate that nanoparticles (SiO2 and TiO2) could be benefi cial for the bonding strength of UF adhesive in harsh environmental conditions.