## 3 Results and Discussion
### Determination of Mechanical Strength  
The results of the flexural and transverse grain compression tests of the wood samples are shown in Figure 8. As shown in Figure 8a, there were significant differences in the results for the chemicals at the same concentration, and the flexural modulus values of the treatments were higher than those of the untreated samples. The flexural modulus values of 103, ZC-103, 120, and ZC-120 were 9.62, 10.06, 10.48, and 12.68 GPa, respectively, and the value of ZC-120 was 111.69% higher than the unprocessed sample (5.99 GPa). The smallest difference between a treatment and the control was observed for 103 (60.10%). In general, the addition of ZnCl\({}_{2}\) or an increase in temperature from 103 \({}^{\circ}\)C to 120 \({}^{\circ}\)C resulted in an increase in the flexural modulus. A high temperature and a relatively low agent fixation rate were more conducive to the rigidity of the wood samples, which was due to the DM/MA internal or external condensation reaction that deposited material in the lumen of the wood cell, causing the cell cavity of the wood to inflate. The deformation was lowest under the ultimate load. The flexibility of the wood originally produced by the empty spaces in the wood was reduced, resulting in increased rigidity [28]. In addition, due to the deposition of the modified chemicals in the cell wall of the wood, the free movement between the polysaccharide chains was reduced, and the rigid structure of the cell wall matrix was improved [9]. However, when the filling amount of the chemicals in the intercellular space reached a certain level, acidic hydrolysis of the catalyst MgCl\({}_{2}\) occurred: since the chemicals inflated the cell wall micropores, the water content in the cell wall was higher than in the sample under the same temperature and relative humidity conditions, and thus the plasticizing effect on the microfibrils was stronger under an external load, and the wood samples were more easily deformed [29]. In addition, the flexural strength was positively correlated with the change in the WPG (Figure 7a), although it decreased with increasing temperature; however, the flexural strength improved after adding ZnCl\({}_{2}\)  
Figure 7: Micrographs of the tangential sections of the wood samples. The magnification is 20 \(\upmu\)m, and the arrows point to the curing chemicals. Among the untreated wood samples (Ctrl), 10% DM + 10% MA were modified by 103, ZC-103, 120, and ZC-120 and are shown in (**a1**), (**b1**), (**c1**), and (**d1**). The micrographs of the resolidified products after the leaching test are shown in (**a2**), (**b2**), (**c2**), and (**d2**), which correspond to (**a1**), (**b1**), (**c1**), and (**d1**). and the bending strength of 103, ZC-103, 120, and ZC-120 was 93.81, 97.29, 58.56, and 67.80 MPa, respectively. ZC-103 had a flexural strength value that was 39.90% higher than that of the untreated samples (69.54 MPa). When ZnCl\({}_{2}\) was added at 103 \({}^{\circ}\)C and 120 \({}^{\circ}\)C (ZC-103 and ZC-120), the bending strength was also slightly improved compared to the groups without ZnCl\({}_{2}\) (103 and 120) because more chemicals were deposited in the cell cavity and the intercellular layer of the cell wall. When the wood was subjected to an external force, the chemicals in the cell cavities and walls increased the compression resistance on the upper surface of the wood and acted as a tensile force on the lower surface of the wood: the change in the integrated stress manifested as an increase in the bending strength of the modified samples [26]. When the temperature was raised from 103 \({}^{\circ}\)C to 120 \({}^{\circ}\)C, a 37.58% decrease in the bending strength was observed (comparison of 103 and 120). The reason was that MA/DM acted as a modifier to crosslink with the macromolecules in the cell walls of the wood.