## 3 Results and Discussion
### Determination of Mechanical Strength
The degree of activity and linkage of the active chemical groups in the wood changed, hydrogen bonding occurred, the connection between the microfibrils was broken, and the catalyst accelerated the hydrolysis of the hemicellulose: drying and high temperatures destroyed the linkage between the cellulose and resulted in a decrease in the bending strength [9; 21]. The STDVAs of the modulus and the strength of the bending were in the range of 0.19-0.88 GPa and 1.54-3.87 MPa, respectively, indicating that the test results of the bending performance were uniform for the 20 replicates and that there was no significant difference between the individual tests. As shown in Figure 8b, the transverse compressive modulus of elasticity was significantly reduced in the treated compared to the untreated samples, and the values of 103, ZC-103, 120, and ZC-120 were 0.23, 0.19, 0.18, and 0.17 GPa, respectively. The value was lowest for 120 cured at 120 \({}^{\circ}\)C, which was 28.00% lower than in the untreated samples. The addition of ZnCl\({}_{2}\) (ZC-120) resulted in a negative effect, indicating that there was more MgCl\({}_{2}\) in the samples. MgCl\({}_{2}\) is a Lewis acid that does not provide oxygen ions during hydrolysis but accepts the free electron pair provided by the oxygen atom on the MA glycosidic bond: It polarizes the bond, making it more susceptible to attack by hydronium ions. The greater the concentration of hydrogen ions, the more easily the hydrolysis occurs, resulting in a decrease in the strength of the cellulose without the protection of hemicellulose [30]. In contrast, the compressive strengths of the cross-grain were 6.52, 7.33, 4.47, and 6.58 MPa (103, ZC-103, 120, and ZC-120, respectively): the value of group B was 68.12% larger than that of the untreated samples (4.36 MPa). In general, an increase in temperature reduced the compressive strength of the grain, whereas the addition of ZnCl\({}_{2}\) increased the compressive strength. The compressive modulus and strength were in the range of 0.16 \(\times\) 10\({}^{-1}\)-0.26 \(\times\) 10\({}^{-1}\) GPa and 0.29-0.99 MPa, respectively. The results of the impact strength test are shown in Figure 9. As shown in Figure 9a, the impact strengths of 103, ZC-103, 120, and ZC-120 were 15.74, 12.31, 13.58, and 8.01 KJ/m\({}^{2}\), respectively. In general, the curing temperature of the modified samples and the addition of ZnCl\({}_{2}\) reduced the impact strength: The minimum value occurred in ZC-120 and was 4.05 times lower than that of the untreated material. The value of 103 was 2.21 times lower. Therefore, the loss of the impact strength  
Figure 8: Flexural strength and modulus (**a**) and transverse compressive strength and modulus (**b**) of the wood samples after treatment with 10% DM + 10% MA in 103, ZC-103, 120, and ZC-120 treatments. was higher at 103 \({}^{\circ}\)C than at 120 \({}^{\circ}\)C. The reduction in impact strength was attributed to the hydrolysis of the polymer inside the wood and the cross-linking reaction of the modifier in the cells. During this process, the moisture content inside the cell wall decreased, the brittleness of the wood increased, and the deposition amount of the modifier increased [31; 32]. More hydronium ions were produced by MgCl\({}_{2}\), resulting in a larger amount of cellulose being hydrolyzed. Figure 8b shows the fracture surfaces of the samples after the impact test. The poplar sample was not broken into two pieces, but a fiber bundle was generated on the surface. In contrast, the modified samples were brittle, the sections were relatively smooth, and there was no fiber bundle. The cross-sections were black, indicating that the cellulose was degraded by high-temperature catalysis. The STDVA was in the range of 1.09-2.62 KJ/m\({}^{2}\), indicating that there were no differences in the 20 replicates.