## 3 Results and Discussion
The lack of a drop in the strength of the band at 1060 cm\({}^{-1}\) indicates that the cellulose's C-O-C bonds have not been harmed by the procedure. It may be argued that the impregnated line particles are to blame for this phenomenon (Table 5 and Figure 1). The absorption bands over 1450 cm\({}^{-1}\) can be assigned to the stretching vibrations of (CO\({}_{3}\))- anions present in the carbonate phase in the sample. The behavior of Ca(OH)\({}_{2}\) adsorbed on the surface was monitored, showing that Ca(OH)\({}_{2}\) continuously transformed into the carbonate phase and crystallization proceeded first through the formation of aragonite-like and then calcium-like carbonates [64]. The presence of a band at 3450 cm\({}^{-1}\) signifies a reduction in the quantity of OH groups, leading to a further decrease compared to the control group. An examination of the FTIR spectroscopy peaks reveals notable alterations in cellulose, hemicellulose, and lignin due to the processing [23; 66; 67]. In contrast to the control group, the peak observed at 2910 cm\({}^{-1}\) is notably diminished. This decrease can be attributed to the asymmetric stretching of C-H methyl and methylene groups [68; 69; 70]. Conversely, a noticeable increase is evident in the peak at 1450 cm\({}^{-1}\) compared to the control group. This peak is characteristic of lignin components and signifies symmetrical tension vibrations in C=O and -COO groups within aromatic rings [71; 72; 73]. Moreover, these changes elucidate the influence of functional groups in the added lime minerals on the wood. Another significant observation is the increase in the 873 cm\({}^{-1}\) band relative to the control group, which can be attributed to the Si-O-Al stretching mode associated with CaO [74; 75]. Additionally, distinct peak bands are discernible at 430 cm\({}^{-1}\)[23; 76]. Those findings suggest that lime minerals were successfully grafted into the poplar wood fibers. Figure 1: FTIR Spectra of the impregnated and unim impregnated black poplar samples. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Spectrum Band Position, cm\({}^{-1}\)** & **Active Wood Mass Group** & **Type of Vibration** \\ \hline
3450–3400 & O-H of alcohols, phenols and acids & O-H stretching \\
2970–2850 & CH\({}_{2}\), CH- and CH\({}_{3}\) & C-H stretching \\
1462–1425 & CH\({}_{2}\) cellulose, lignin & C-H deformations \\
1060–1025 & C-O-C & Deformation \\
876 & Anti-symmetric out-of-phase stretching in pyranose ring & Stretching in pyranose ring \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Match of wood functional groups to IR bands of spectra [65; 66]. * DTG/TGA analysis The TGA and DTG thermograms of the control and impregnated black poplar samples are plotted in Figures 2 and 3. The provided data in Table 6 summarize the initial decomposition temperature (T\({}_{0}\)), maximum degradation temperature (T\({}_{\text{max}}\)), final temperature (T\({}_{\text{f}}\)), and residual weight (RW, %) for the wood samples, both impregnated and control, with calcium hydroxide. The onset of degradation occurred at 140 \({}^{\circ}\)C for both the impregnated and non-impregnated black poplar samples, signifying the removal of water and certain extractive components from the specimens up to this temperature [77; 78]. After 140 \({}^{\circ}\)C, the decomposition process  
Figure 3: DTG thermograms of the control and impregnated black poplar samples. Figure 2: TGA thermograms of the control and impregnated black poplar samples. continued until 476 \({}^{\circ}\)C in the control sample, between 494 and 531 \({}^{\circ}\)C in the samples impregnated with the immersion method, and between 532 and 584 \({}^{\circ}\)C in the samples impregnated with the vacuum method.