## 3 Results
### FTIR-ATR Analyses  
In the FTIR spectrum of sample 1 (Figure 6 top left), the characteristic maxima of unmelted \"new\" BBRM (1417 and 872 cm\({}^{-1}\)) are still detectable, although their intensity \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Test Specim** & \multicolumn{2}{c}{**Dimensions, mm**} & \multicolumn{2}{c}{**Drift. mm**} & \multicolumn{2}{c}{**Destructive Force**} & \multicolumn{2}{c}{**Flexural Strength F\({}_{\mathbf{f}}\)**} \\
**Designation** & **Side b, mm** & **Thickness, mm** & **F\({}_{\mathbf{f}}\), N** & \multicolumn{2}{c}{**N/mm\({}^{2}\)**} \\  & & **Thickness, mm** & & & **Value** & **Average** \\ \hline
1-1 & 101 & 31 & 10 & 593.77 & 0.92 & \\
1-2 & 107 & 38 & 10 & 666.11 & 1.55 & 1.24 \\ \hline
2-1 & 104 & 40 & 8 & 3349.28 & 3.02 & \\
2-2 & 110 & 40 & 8 & 3119.39 & 2.66 & 2.84 \\ \hline
3-1 & 101 & 43 & 8 & 1829.31 & 1.47 & \\
3-2 & 101 & 43 & 6 & 2908.63 & 2.34 & 1.91 \\ \hline
4-1 & 101 & 43 & 10 & 2329.19 & 1.96 & \\
4-2 & 103 & 40 & 10 & 2254.16 & 2.05 & 2.01 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Experimental data of flexural strength of the test specimen. The gap between the supports of the press was 100 mm in all tests. Figure 4: Compressive displacement of test series 1 (**top left**), 2 (**top right**), 3 (**bottom left**) and 4 (**bottom right**). The numbers shown in the legends are the identification numbers of the individual test specimens. Figure 5: (**Left**): Compressive displacement of test series 1 (identification numbers 1 and 2 as shown in the legend) and 2 (identification numbers 3 and 4); (**Right**): Compressive displacement of test series 3 (identification numbers 9 and 10) and 4 (identification numbers 11 and 12). has been significantly reduced. The maximum at 1417 cm\({}^{-1}\) partially overlaps with the -CH\({}_{2}\) -scissoring deformation vibration peak at 1460-1470 cm\({}^{-1}\). Additionally, a shift is observed in the 1018 cm\({}^{-1}\) signal to 998 cm\({}^{-1}\), indicating alterations in the C-O bond system [24]. These changes are attributed to heating the material to approximately 200 \({}^{\circ}\)C.  
The FTIR spectrum of sample 2 is presented on Figure 6, top right. Interestingly, although the spectrum of BBRM normally includes a signal at 697 cm\({}^{-1}\), this signal is absent in 2. The absence of this signal in sample 2 may result from the thermal treatment. This hypothesis could be tested by heating pure BBRM, which originally shows the signal, at the same temperature. Furthermore, signals specific to the C-H bond stretching vibrations in polypropylene, typically found in the 2800-3000 cm\({}^{-1}\) range, are not detectable thus proving that polypropylene is absent in the waste plastic. However, signals characteristic of polyethylene are present. The FTIR spectrum of sample 3 is presented on Figure 6, bottom left. The FTIR spectrum of this sample closely resembles that of sample 2, with a few notable differences. Thermal treatment appears to have caused the release of several compounds from the BBRM, particularly water, as indicated by a significant decrease in the intensity of O-H stretching vibrations at 3300 cm\({}^{-1}\) and a reduction in bending vibrations at 1626 cm\({}^{-1}\). Additionally, two weak signals have emerged at 3397 cm\({}^{-1}\) and 3533 cm\({}^{-1}\), corresponding to vibrations of either OH or NH groups [27]. To determine their origin, separate thermal treatments of the starting materials should be conducted to assess their effect on the FTIR spectrum. These maxima may have been present in the original material but masked by  
Figure 6: FTIR spectra of samples 1 (100% remelted “new” BBRM; (**top left**)), 2 (45% remelted “new” BBRM, 45% “old” BBRM, and 10% PE waste; (**top right**)), 3 (90% “old” BBRM and 10% PE waste, (**bottom left**)), and 4 (90% “new” BBRM and 10% PE waste, (**bottom right**)). the high water content. Upon water removal at elevated temperatures, absorption maxima of free OH groups from cellulose may become apparent.