Urea–formaldehyde (UF) resin is the most important used adhesive in the production of wood-based composite panels, such as particleboard, medium-density fiberboard, oriented strand board and plywood. The aim of this work was to investigate the influence of nanocellulose, boric acid and borax on the chemical performance properties of UF resin. UF resin was reinforced with various loading levels of nanocellulose, boric acid and borax. Formaldehyde emission, gel time, solid content, viscosity, pH, specific gravity, shelf life and Fourier transform infrared spectra were evaluated as indicators of chemical performance. The findings showed that the formaldehyde emission of hybrid UF resin reinforced with nanocellulose/boron compounds decreased by up to 31.25%. The use of the reinforcement technique in the resin caused an increase in shelf life, viscosity and gel time but caused a reduction in the solid content of the resin. The apparent specific gravity of the resin was not influenced by the addition of nanocellulose/boron compounds. It was concluded that the chemical performance properties of UF resin could be enhanced by using proper nanocellulose, boric acid and borax loading levels. By using the reinforcement technique, it was possible to produce low-formaldehyde-emitting adhesives so that environmentally friendly products could be manufactured.

The main objective of this study was to evaluate the dynamic mechanical thermal analysis (DMTA), mechanical, physical and wettability properties of hybrid composites developed from sustainable green materials, jute fiber and wood particles that were manufactured by using the vacuum-assisted resin transfer molding technique. The storage modulus, loss modulus and tan δ values of the hybrid composites were also determined to evaluate the DMTA performance. The results showed that the storage modulus of jute/polyester resin is superior to those of the jute–wood/polyester hybrid and wood/polyester up to the glass transition temperature (T_g). However, for temperature ranges higher than T_g, the stiffness of hybrid composites increased relatively. The T_gvalues from loss modulus and tan δ peaks support this effect of hybridization. Tests on mechanical properties showed that the jute/polyester specimens had a significant increase in tensile strength compared with the jute–wood/polyester hybrid and wood/polyester specimens. The results of tests of physical properties showed that the wood/polyester specimen had the lowest values of thickness swelling, water absorption and moisture content compared with the jute/polyester and jute–wood/polyester composites. The highest contact angle was obtained from composites made of wood/polyester. It could be concluded that the composites with enhanced performance could be used as novel green composites in various sectors.

The aim of the study was to investigate the effect of two different types of lignosulfonate (LS1 and LS2) added to urea–formaldehyde adhesive on the performance properties of five-layered plywood panels. The physical properties (density, thickness swelling, water absorption and moisture content), mechanical properties (modulus of rupture, modulus of elasticity and bonding quality) and free formaldehyde emission were evaluated in accordance with international standards. The results show that the lignosulfonate used in the production of plywood panels improves not only mechanical properties but also physical properties. Furthermore, the reinforcement caused by the use of proper lignosulfonate resulted in a decrease in free formaldehyde content. Using 3% LS1, eco-friendly plywood panels with improved physical (max. 22.40%) and mechanical properties (max. 42.40%) and drastically reduced free formaldehyde emissions (max. 16.27%) can be produced. It was concluded that lignosulfonates, as a byproduct of the pulping industry, can be used as a high-value additive in formaldehyde-based adhesives for engineered wood composites.