## 3 Results and Discussion
### FTIR Analysis  
Susceptibility to degradation depends on the presence of specific chemical groups in the molecule. The easily hydrolysable ester, amide, and urea groups accelerate the polymer decomposition [39; 40]. Since photodegradation of polymeric materials takes place most intensively in the surface layer, up to approx. 10 \(\upmu\)m [41], the surface of degraded foams was scraped (1t series) and FTIR spectra of 1t foams were compared with the 0t series spectra (not subjected to degradation). On the basis of the FTIR analysis (Figure 4a,b), the following groups (Table 7) can be distinguished in the construction of all foams: N-H, CH, -N=C=O, -N=C=N, C=O in urethane, isocyanurate, -C=N in the trimer, and C-O. The polyurethane-polyisocyanurate structure of the obtained foams has been confirmed [1; 5; 8]. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Foam** & \begin{tabular}{c} **CS\_0t** \\ **(kPa)** \\ \end{tabular} & \
\begin{tabular}{c} **CS\_1t** \\ **(kPa)** \\ \end{tabular} &
\begin{tabular}{c} **CV** \\ **(\%)** \\ \end{tabular} \\ \hline W & \(251.6\pm 6\) & \(140.5\pm 4\) & \(74.7\pm 2\) \\ WU & \(361.4\pm 9\) & \(256.2\pm 6\) & \(70.9\pm 2\) \\ C5 & \(212.7\pm 6\) & \(200.1\pm 5\) & \(94.1\pm 2\) \\ C10 & \(160.4\pm 4\) & \(143.9\pm 4\) & \(89.7\pm 2\) \\ C15 & \(147.3\pm 3\) & \(126.6\pm 4\) & \(86.0\pm 2\) \\ CU5 & \(121.4\pm 3\) & \(151.1\pm 4\) & \(124.4\pm 3\) \\ CU10 & \(109.4\pm 2\) & \(132.8\pm 4\) & \(121.4\pm 3\) \\ CU15 & \(91.9\pm 2\) & \(109.6\pm 3\) & \(119.2\pm 3\) \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Compressive strength (CS) and compressive strength ratio (CV): CS_0t—measured before condition; CS_1t—measured after one-week condition. \begin{table}
\begin{tabular}{c c} \hline \hline
**Band, cm\({}^{-1}\)** & **Bond** \\ \hline
3325 & N–H \\
2930 & C-H \\
2276 & -N=C=O \\
2137 & -N=C=N– \\
1713 & C=O in urethane bond \\
1596 & N–H \\
1512 & N–H \\
1411 & Isocyanurate ring \\
1225 & C=N in trimer \\
1076 & C–O \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Results of the FTIR analysis. The FTIR spectra (Figure 4a) of the foams with a maximum cinnamon extract content (15 wt%) and with flame retardant content, before degradation (C15_0t) and after degradation (C15_1t) where compared. The FTIR spectra of the foam with flame retardant (C15_0t series) subjected to degradation (C15_1t) showed that after degradation the intensity of the bands associated with the bonds (_red lines_) increases: N-H (3325 cm\({}^{-1}\)), CH (2930 cm\({}^{-1}\)), -N=C=O (2276 cm\({}^{-1}\)), -C=O (1713 cm\({}^{-1}\)), -NH (1596 cm\({}^{-1}\)), -N-H (1512 cm\({}^{-1}\)), isocyanurate ring (1411 cm\({}^{-1}\)), -C=N in the trimer (1225 cm\({}^{-1}\)), -C=OH (1076 cm\({}^{-1}\)). The bond associated with the -N=C=N- (2137 cm\({}^{-1}\), _green line_) decreased. The figure (Figure 4b) compares the foams with a maximum cinnamon extract content (15% wt.) without flame retardant before degradation (CU15_0t) and after degradation (CU15_1t). The spectra of  
Figure 4: FTIR of: (**a**) C15_0t and C15_1t; and (**b**) CU15_0t and CU15_1t. FTIR foams without flame retardant (CU_0t series) subjected to degradation (CU_1t) showed that after degradation the intensity of bands related to bonds: CH (2930 cm\({}^{-1}\)), -N=C=O (2276 cm\({}^{-1}\)), -N=C=N- (2137 cm\({}^{-1}\)), -C=O (1713 cm\({}^{-1}\)), -NH (1596 cm\({}^{-1}\)), -NH (1512 cm\({}^{-1}\)), isocyanuric (1411 cm\({}^{-1}\)), -C=N in the trimer (1225 cm\({}^{-1}\)) and -C=OH (1076 cm\({}^{-1}\)) decreases after degradation (_green line_). Only the band associated with the -OH (3325 cm\({}^{-1}\)) groups did not change (_grey line_). Antioxidant properties of flavonoids were determined by the presence of hydroxyl groups in both rings, the isomeric of their location, and the presence of a double bond and a carbonyl group in the heterocyclic ring [42]. Bands whose intensity increased were prone to degradation.