The particle size of rice straw also affected the IB and MOR val-ues of RSTIB, as shown in Table 6. It was found that IB and MOR in creased with increasing particle size from the results for F-, S-and L-type boards. Compared with wood particles, the outer surface of the rice straw contains a high amount of hydrophobic wax and inorganic silicon [47–49], which results in weak bonding between particles. As the amounts of fine particles increased, the proportion of rice straw surface that contains wax and inorganic siliconwas decreased, and consequently