Effects of Density Profile on Bending Strength of Commercial Particleboard

Face layer density is widely known to be important for increasing bending strength (i.e., modulus of rupture [MOR]), whereas outer core layer density is not regarded as such. This study reports the importance of the outer core layer density for commercial particleboards. The core and face layers were manufactured with coarse and fine particles, respectively. The coarse particles increased MOR because of the long wood fibers retained in the particle, whereas fine particles did not increase MOR because of the absence of long wood fibers. Long wood fibers in the outer core layer, as opposed to face layers, increase MOR. Moreover, the sampling position of the density profile specimen was important for the MOR. The MOR was influenced with the density profile specimens obtained near the center of the MOR specimen; thus, the low-density part near the center of the MOR specimen exerted a large influence by significantly decreasing the MOR.