The demand for wood-based materials as an alternative to plywood is increasing, and a synthetic adhesive is typically used for the fabrication of such materials. The identification of replacements for standard adhesives poses a major challenge. In this study, we investigated the mechanical properties of particleboard bonded by cellulose nanofiber (CNF) and compared the mechanical properties of particleboard bonded by CNF with those of particleboard bonded by adhesive. CNF was added together with wood particles during the fabrication process. The target CNF addition amounts were 0, 3, 5, 10, and 20 weight percent. The bending and internal bond strengths of the particleboard with CNF increased, and its water absorption decreased as CNF content increased. The comparison between the boards prepared with adhesives and those with CNF showed that the properties of boards prepared with 20 weight percent CNF were comparable to those of boards prepared with 1 weight percent synthetic adhesive.

The objective of this study was to investigate the lab-scale manufacturing process of insulation fiberboard (IFB) with cellulose nanofibers (CNFs) and evaluate the effects of CNFs on the mechanical and physical properties of the IFB. Because the fabricated IFBs with CNFs had a homogeneous appearance, it was assumed that CNFs can be easily dispersed within IFB by adding them during the mixing stage of the wet process of wood-based board production. The results for the IFBs with CNFs revealed that the density and bending properties increased, while the thickness decreased with an increase in the CNF addition ratio. Furthermore, after the water absorption test, the weight change rates of the IFBs decreased, and the thickness swelling rates increased. Although the size of the specimens was different from the size in JIS A 5905 (Japan Standards Association 2014), the modulus of rupture (MOR) values of IFBs with a target density more than or equal to 0.20 g/cm3 were higher than the value of A-class IFB in the standard for all CNF addition ratios. In addition, lower thermal conductivity may be realized under similar MOR values by adding CNFs to IFB. On the other hand, to produce CNF-reinforced IFBs with target density/thickness, it is necessary to develop a method for decreasing the cohesive force derived from CNF aggregation and the compressive force originating from the water surface tension caused by the high water retention of CNFs.