## 3 Results and Discussion
### Dimensional Stability  
The curve depicting the shrinkage rate of the wood sample boards during drying is presented in Figure 5. The regression equations and \(R^{2}\) are also presented. An extremely high nonlinear or linear relationship is exhibited between shrinkage and MC in the width and thickness directions (\(R^{2}\)\(>\) 0.8). The shrinkage rate of the three sets of experiments decreased with an increase in MC. When MC decreased to about 30%, the shrinkage of wood in both the width and thickness directions markedly increased. The reason might be that when MC was below the FSP, the gap between the microfibrils and micelles in the cell wall shrank after the absorbed water was discharged, causing a reduction in the thickness of the cell wall and abrupt shrinkage. Figure 5 shows that during drying, the T1 group exhibited the largest amount of dry shrinkage, followed by T3 and then T2.  
The final shrinkage rate of the three groups is shown in Figure 6. The shrinkage rates of T1 in the width and thickness directions reached 4.26% and 4.31%, respectively, and STDEVA fluctuated  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Materials** & **Initial MC (\%)** & **Final MC (\%)** & **Time (h)** & **Average Drying Rate (\%/h)** \\ \hline T1 & 119.34 \(\pm\) 0.59 & 11.79 \(\pm\) 0.77 & 205 & 0.52 \\ T2 & 105.20 \(\pm\) 2.35 & 12.31 \(\pm\) 1.74 & 336 & 0.28 \\ T3 & 120.11 \(\pm\) 11.73 & 13.87 \(\pm\) 0.42 & 318 & 0.33 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Final moisture content after drying.  
Figure 5: Curve depicting the shrinkage rate of T1, T2, and T3 during drying. 1# and 2# shrinkage rate curves of T1 (**a**), (**b**); 1# and 2# shrinkage rate curves of T2 (**c**), (**d**); 1# and 2# shrinkage rate curves of T3 (**e**), (**f**).  
between 0.08% and 0.11%, which proved the small variability of the two sample boards; the shrinkage rates of T2 in the width and thickness directions reached 0.89% and 0.95%, respectively (which were considerably lower than those of T1), and the STDEVA fluctuated between 0.04% and 0.05%. The shrinkage rates of T3 in the width and thickness directions were 3.02% and 3.53%, respectively, and the STDEVA fluctuated between 0.07% and 0.10%. Analysis of the STDEVA of T1, T2, and T3 indicate that the two sample boards in each group exhibited a small variability, and the results were in accordance with statistical standards. After immersion, wood shrinkage was significantly reduced. The ASEs of the T2 group in the width and thickness directions were 79% and 78%, respectively, and the STDEVA fluctuated between 0.47% and 1.61%. The reason is that wood mainly consists of cellulose, hemicellulose, and lignin; in addition, a large number of hydroxyl groups are found on the cellulose and hemicellulose molecules, and the hydroxyl groups are hydrophilic. Owing to the action of the hydroxyl groups, wood absorbs and evaporates moisture as a function of external temperature and humidity, resulting in shrinkage or swelling, hence the unstable wood size, internal stress, warpage, deformation, and cracking. However, DM could react with a large number of hydroxyl groups; thus, the reduction in hydroxyl content could alleviate the shrinkage of wood to a certain extent. Simultaneously, as the drying process progressed, the modifiers gradually solidified in the cell cavity, increasing the stability of the cell-wall structure and improving the dimensional stability of the wood. Compared with T1, T3 increased in dimensional stability in the width and thickness directions, but only by 29% and 18%, respectively. The standard deviation ranged from 3.21% to 4.10%. A deviation of nearly 11% was observed, which further indicates that a higher initial MC led to uneven curing of modifiers during immersion.