## 3 Results and Discussion
The values were found to be between 2.77 and 5.22. Compared to the control group, the B group exhibited the smallest alteration, registering a 21.3% change, while the G group displayed the most substantial variation with an 88.4% shift. Ra increases the surface roughness of the impregnation process. It is explained that this situation is related to the increase in the amount of substance on the surface as the amount of retention increases [54; 55; 56]. The contact angle values of the groups included in the study are shown in Table 4. It has been determined that as the lime concentration ratio increases, the contact angle increases. The values were found to be between 41\({}^{\circ}\) and 68\({}^{\circ}\). It has been determined that the highest hydrophobic sample group with a contact angle of 68\({}^{\circ}\) is obtained with group G, which increases hydrophobicity by 65.8% compared to group A. Similar to the findings for water absorption, increasing lime particles increased the contact angle, which was significantly higher in woods treated and impregnated [57; 58; 59; 60]. The LOI values of the sample groups are summarized in Table 4. The values were found to be between 23.16% and 31.23%. It has been determined that the highest fireproof sample group with a LOI of 31.23% is obtained with group G, which increases fire resistance by 34.8% compared to group A. In wood impregnated with lime minerals, the LOI value increased as the lime ratio increased. LOI values were found to be between 26.75% and 30.08% in the immersion method and between 28.27% and 31.23% in the vacuum method. The vacuum method is posited to yield a superior insulating effect against heat transfer compared to the immersion method. The retardation of flame propagation appears to stem from the lime's capacity to facilitate the generation of char. This ensuing coal coating forms an insulating barrier, impeding the passage of combustible gases that sustain the flame and displaying resistance to heat transfer [61; 62; 63]. * FTIR analysis was employed to discern the functional groups and chemical interactions among the materials. The FTIR spectrum exhibited observable shifts in the characteristic peaks of cellulose, hemicellulose, and lignin, contingent upon the impregnation method and the ratio of lime additive. FTIR spectra encompassing the impregnated black poplar samples, as well as the control samples, were recorded over the wavelength range of 4000 to 400 cm\({}^{-1}\). The control group and the groups impregnated with both impregnation methods show absorbance peaks for wood fibers at 876 cm\({}^{-1}\) (Si-O-C), 1060 cm\({}^{-1}\) (C-O-C), \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Sample Type** & **Surface Roughness (Ra) (\(\parallel\))** & **Changes (\%)** & **Contact Angle (\({}^{\circ}\))** & **Changes (\%)** & **LOI (\%)** & **Changes (\%)** \\ \hline A & 2.77 (0.31) 1 a2 & - & 41 (4.66) a & - & 23.16 (2.55) b & - \\ B & 3.36 (0.99) b & 21.3 & 54 (4.34) b & 31.7 & 26.75 (3.07) b & 15.5 \\ C & 3.90 (0.83) c & 40.8 & 59 (5.27) c & 43.9 & 28.44 (2.43) b & 22.8 \\ D & 4.12 (0.46) d & 48.7 & 62 (4.02) d & 51.2 & 30.08 (1.94) b & 29.8 \\ E & 3.58 (0.60) c & 29.2 & 61 (3.95) c & 48.8 & 28.27 (1.64) b & 22.0 \\ F & 4.35 (0.97) d & 57.0 & 66 (6.26) e & 60.9 & 30.62 (2.44) b & 32.2 \\ G & 5.22 (0.44) e & 88.4 & 68 (6.31) e & 65.8 & 31.23 (2.74) b & 34.8 \\ \hline \hline \end{tabular}  
* Standard deviation, 2: The same letters in a column of surface roughness, contact angle, and LOI are not significantly different (\(p\leq 0.01\)). The post hoc tests (Duncan) for the surface roughness, contact angle, and LOI were analyzed separately because the interaction factor was significantly different.  
\end{table} 
Table 4: Surface roughness, contact angle, and LOI properties of impregnated wood samples. 2910 cm\({}^{-1}\) (C-H), and 3450 cm\({}^{-1}\) (O-H). In addition, the impregnated groups showed a new increase at 1450 cm\({}^{-1}\) for C=O stretching vibration.