## 3 Results and Discussion
### Fourier-Transform Infrared Spectroscopy
Although DM underwent a polycondensation reaction with the O-H inside the wood, the added amount was greater than the consumption. The absorption peaks at 1731 cm\({}^{-1}\) belonged to the acetyl and carboxyl groups of wood hemicellulose, nonconjugated ketones in lignin, carbonyl compounds, ester groups, etc. The absorption peaks at this point were shifted after the introduction of  
Figure 6: Fourier-transform infrared (FTIR) spectra of samples treated with different methods: (**a**) shows the FTIR of the samples in different treatments (Ctrl: untreated wood samples; group 1:10% DM + 10% MA; group 2:10% DM + 10% MA + ZnCl\({}_{2}\); group 3:10% DM + 10% MA, cured at 103 \({}^{\circ}\)C; group 4:10% DM + 10% MA + ZnCl\({}_{2}\), cured at 103 \({}^{\circ}\)C; group 5:10% DM + 10% MA, cured at 120 \({}^{\circ}\)C; group 6:10% DM + 10% MA + ZnCl\({}_{2}\), cured at 120 \({}^{\circ}\)C; group 7:10% DM + 10% MA, solidified at 120 \({}^{\circ}\)C until the water evaporation was complete; group 8:10% DM + 10% MA+ ZnCl\({}_{2}\), solidified at 120 \({}^{\circ}\)C until the water evaporation was complete. (**b**) Here, the FTIR spectra of the modified samples in different treatment groups are shown, and (**c**) shows the change in the color of the chemicals when heated to different temperatures at 10% MA. DM, and an amide acetyl group (O = C-N) was formed in the wood samples. In addition, the increase in the peak of the C-N bond stretching vibration at 1457 cm\({}^{-1}\) also proved that DM reacted with the wood. At 1157 cm\({}^{-1}\), the absorption peak of C-O-C gradually increased due to the crosslinking reaction between the wood and DM and the condensation reaction of DM to form an ether bond. The absorption peaks of the untreated wood at 1260 and 1224 cm\({}^{-1}\) were attributed to the vibration of the carboxyl functional groups in xylan and other hemicelluloses [18; 27]. In the experimental group, the stretching vibration was enhanced, indicating that wood modification occurred and that the chemicals not only filled the cell space between the wood cell and the intercellular space but that crosslinking had occurred with certain groups inside the wood to form carboxyl groups. The highest absorption peak of the infrared spectrum of the lanthanum-modified wood occurred at 1050 cm\({}^{-1}\) and was caused by the stretching vibration in the alcohol and ether groups in the polysaccharide. The stretching vibrations in the treated samples were obviously strengthened by the vibration of various functional groups in the lignin, indicating chemical crosslinking with cellulose and DM in the wood. The peaks of 103 and ZC-103 were the largest, indicating the largest fixation rate of DM/MA inside the wood and a large amount of alcohol and ether. The peaks of the 120 and ZC-120 groups were lower than those of groups 103 and ZC-103 because the chemicals were more volatile at 120 \({}^{\circ}\)C, which was not conducive to the fixation of the chemicals. In summary, the addition of ZnCl\({}_{2}\) had no significant effect on the functional groups of the modifier, indicating that no acidic substances able to affect the mechanical properties of the wood were generated in the high-temperature atmosphere. The samples cured at 120 \({}^{\circ}\)C had excellent resistance to water leaching, but the amount of solidification inside the wood was lower than in the samples cured at 103 \({}^{\circ}\)C because the modifier was more volatile and was not easily fixed at 120 \({}^{\circ}\)C.