# Some of the Physical and Mechanical Properties of
## 3 Results and Discussion
### Mechanical Properties of the Panels  
Bending properties of the panels, namely MOE and MOR are illustrated in Figure 2. Both MOE and MOR values of the panels made from coarse particles were higher than those made from fine particles. The MOE values for the boards made with coarse and fine particles were 1.49 and 1.31 GPa, respectively. Meanwhile, the MOR values, which indicated the bending strength, were 13.43 MPa for coarse particles and 11.37 MPa for fine particles. Panels made with coarse particles had IB values of 0.33 MPa, while the corresponding value was 0.57 MPa for those made with fine particles (Figure 3). Meanwhile, the SWR of coarse particleboard was 558 N, while that for fine particleboard was 441 N, as can be seen in Figure 4. The results of the ANOVA from the comparison test showed that the particleboard samples made with coarse and fine particles in this study were not significantly different for all the parameters of mechanical properties that were tested. Referring to Table 1, the properties of the samples that met the JIS requirements [23] were the MOR and IB of coarse particleboard for its two standard types (Type 8 and Type 13), while fine particleboards met the MOR requirements for Type 8. Neither type of particleboard qualified for the MOE values of either Type 8 or Type 13 for over 2 and 2.5 GPa, respectively. Meanwhile, the particleboards in this study that met [25] were only coarse particleboards with regards to the MOR and IB properties. The MOR values for the coarse particleboard were close to the standard values, while all mechanical properties on the fine particleboard did not met the standard. Both types of particleboard met the qualification for SWR as stipulated in the JIS standard.  
Figure 1: (**a**) Thickness swelling (TS); (**b**) water absorption (WA) of particleboards with different particle sizes. Values followed by different letters are statistically different at \(p<0.05\).  
Figure 3: Internal bond strength values of the samples. Values followed by the same lowercase letters are statistically not different at \(p<0.05\).  
Figure 2: Bending characteristics of particleboard made with different particle sizes. Values followed by the same letters are statistically not different at \(p<0.05\).  
The particle size and geometry are two important raw material characteristics influencing almost all properties of the panels including IB and screw withdrawal resistance of the panel [42]. A study on the IB mechanical properties in bamboo particleboards found that the IB values were higher with a decreased particle size [7]. Another study on wood particleboard also determined similar results [43]. In this work, it was also observed that boards made with coarse particles had lower IB values than those with fine particles. Internal bond strength values of 0.57 and 0.33 MPa were determined for the panels made from fine and coarse particleboards, respectively. The study on composite boards made from veneer waste and having particle sizes of 0.5 to 2.0 mm had an IB value of 0.58 N/mm\({}^{2}\)[11], while [7] found an IB value of 0.25 N/mm\({}^{2}\) for the particleboard with a particle size of \(-35+40\) mesh. In a comparison to the IB values from commercial bamboo particleboards, ref. [2] found a range of IB values from 0.34 to 1.50 N/mm\({}^{2}\) for boards using various resin and resin contents. However, the SWR values on the face surface of the boards were higher for the coarse compared with the fine particleboard. Using the same bamboo species of \(D\). _asper_ with different particle sizes, ref. [7,11] found the SWR (face) values of 499 and 706 N, respectively.