## 2 Experimental Procedures
### Sample Preparation  
The process of sample preparation is shown in Figures 1 and 2 and is described in the following paragraph.  
Rice straw was collected from local farming operation and crushed with by a hammer mill into different particle sizes of 10-40 mm. After this, the straw particles were screened to eliminate fine particles and dust from the straws.  
The treatment of rice straw was made according to [10] and the preparation of starch was based on [14]. A desired amount of straw was sprayed with resin material and afterwards was sufficiently mixed for 8 min. The mixture was then filled into a steel mold of \(700\times 350\) mm and placed on a wooden board. After filling the first layer, the straw was manually compacted to ensure that the mold was properly filled. The steel mold was then removed, and the first pressing was carried out. This was done with a manually controlled hydraulic press and took about 2 min. After this primary press, the samples were placed between the heated platens of the hot press, which were heated to a constant temperature of 180 \({}^{\circ}\)C and applied the pressure of a 210 bar to ensure optimal curing of the resin material. It took 4 min to reach constant temperature and 8 min until the hot-pressing process was completed. After adjusting the edges of the samples with a utility knife, the finished boards were cut to desired length, width, and to square the edges.  
Various recipes of particleboards with different parameters were prepared for testing and are shown in Table 1. The variated parameters include resin ratio (10%, 12%, and 14%), resin type (Urea formaldehyde (UF), and cornstarch (CS)), waste type (rice straw and flax shives), particleboard density (0.3, 0.5, and 0.7 g/cm\({}^{3}\)), and straw treatment (hot water and sodium hydroxide (NaOH)).  
\begin{table}
\begin{tabular}{c c c c c c} \hline \multirow{2}{*}{**Samples**} & \multirow{2}{*}{**Type of Waste**} & **Ratio of Resin** & \
\begin{tabular}{c} **Density of** \\ **Particleboard** \\ **(g/cm\({}^{3}\))** \\ \end{tabular} & \multirow{2}{*}{
\begin{tabular}{c} **Treatment of** \\ **Straw** \\ \end{tabular} } & \multirow{2}{*}{**Type of Resin**} \\  & & & & \\ U\({}_{10}\) & Rice straw & 10 & 0.7 & Untreated & UF \\ U\({}_{12}\) & Rice straw & 12 & 0.7 & Untreated & UF \\ U\({}_{14}\) & Rice straw & 14 & 0.7 & Untreated & UF \\ D\({}_{0.3}\) & Rice straw & 12 & 0.3 & Untreated & UF \\ D\({}_{0.5}\) & Rice straw & 12 & 0.5 & Untreated & UF \\ N & Rice straw & 12 & 0.5 & NaOH & UF \\ W & Rice straw & 12 & 0.5 & Hot water & UF \\ S & Rice straw & 10 & 0.5 & Untreated & CS \\ Z & Rice straw & - & 0.5 & Untreated & without resin \\ F & Flax shaves & 12 & 0.5 & Untreated & UF \\ \hline \end{tabular}
\end{table}
Table 1: Designed particleboard recipes.  
Figure 1: Sample manufacturing processes: (**a**) Mild rice straw, (**b**) Mixing straw with resin material, (**c**) Straw mix with resin material in mold, (**d**) Straw mold before primary press, (**e**) Straw mold put in platens before primary press, (**f**) Straw mold after the primary press, (**g**) Particleboard before hot press, (**h**) Particleboard between heated platens of the press, (**i**) Particleboard after the hot press, and (**j**) Particleboard after trimming.