The reason for the highest MOR obtained with 10% replacement at the 1:5 ratio could be due to the increased binding capability of RBA in the particleboard. However, at the high RBA replacement ratio, the MOR was significantly lower than the control. In a similar manner as the tensile strength, up to 30% PMDI replacement with RBA solids (ratio 1:1), the MOR characteristics were the same as the control, which corresponded to about 15% moisture in the particleboard before hot pressing.