Stability and Rheological Behavior of Nanocellulose-modified UF Resin Compositions

The aim of this work was to investigate the influence of nanocellulose on the storage stability and rheological properties of urea formaldehyde (UF)-based adhesive compositions for wood-based panels. Three types of UF resins characterized by different F/U molar ratios were used for this research. Resin modifications with nanocrystalline cellulose and a nanofibrillated cellulose content of 1.0% to 5.0% by dry weight of resin were prepared. The flow curve characteristics and storage stability were studied. The viscosity values mainly depended upon the type of nanocellulose used, as well as its loading in the composition. The UF resins modified with nanocrystalline cellulose kept their rheological behavior and proper viscosity after 4 weeks in storage, which lowered the percentage of viscosity retention by approximately 1.5 times compared with that of industrial resins. Nanocrystalline cellulose might be used as a stabilizer in resin compositions during long-term storage, while nanofibrillated cellulose might act as a thickening agent through the limited extent of loading in a composition.