Water-resistant wood adhesive without plasticizers: synthesis and characterization

Commercially available polyvinyl alcohol (PVA) stabilized polyvinyl acetate (PVAc) emulsion adhesives produce affordable, colourless gluelines with an extremely durable connection to various types of wood. At room temperature, the adhesive solidifies as a result of water evaporation. Plasticizers are required for the PVAc emulsion; however, they have drawbacks that affect their mechanical and thermal properties. On the other hand, they demonstrate limited strength at high relative humidity and high temperatures and are neither heat- nor moisture-resistant. The goal of the present research is to develop a plasticizer-free glue by copolymerizing vinyl acetate (VAc), vinyl neodecanoate (VeoVa), and methyl methacrylate (MMA) with butyl acrylate (BA). The sample with BA is also put together with PVA solution, aluminium nitrate, and preservatives, and it is tested with the copolymer sample without BA. The viscosity, pH, water contact angle, scratch resistance of the films, and differential scanning calorimetry measurements were used to analyse the physical, thermal, and mechanical properties of adhesives containing BA. The shear strength of the samples on the wood specimen was evaluated in dry and wet conditions in accordance with EN 204-205. The viscosity of the adhesives increased as the BA concentration increased. The hardness of the adhesive films was adversely impacted by the addition of BA. The hydrophobic properties of the BA addition were confirmed through measurements of the water contact angle. The tensile shear strength value evaluated under dry conditions after 6 h of drying demonstrated a 9.5% increase on the 1 wt% BA sample in comparison to pristine glue. Analysis of performance in wet situations also showed that BA addition improved performance. By adjusting the amount of BA, a novel water-resistant crosslinked emulsion adhesive without any plasticizer can be developed with enhanced water resistance and performance. The technique used to increase the wood adhesive's resistance to moisture was affordable, plasticizer-free, and environmentally safe.