## 3 Results and Discussion
### FTIR Analysis
Density (d), Water Absorption (WA), Absorbability (A), Softening Point (SP), Brittleness (B), and Content of Closed Cells (CC)  
The apparent density of the foam affects its mechanical properties. The main advantage of PU materials, which are used in civil engineering, is their low density (and also good durability) [3]. The decrease in foam density is also economically advantageous. The results of research on foams modified by cinnamon extract (Table 8) showed that the apparent density of C_0t foams decreased from 39.67 kg/m\({}^{3}\) (W_0t) to 33.97 kg/m\({}^{3}\) (C15_0t). For a series of foams without commercial flame retardant -FR (CU_0t), density slightly decreased from 30.94 kg/m\({}^{3}\) (CU5_0t) to 29.43 kg/m\({}^{3}\) (CU15_0t). The density of the reference foam WU_0t was 49.6 kg/m\({}^{3}\). The reason for the decrease in foam density was most probably the incorporation of cinnamon compounds (e.g., flavonoids, chlorogenic acids, phenol acids and others) into the structure [42; 43; 44]. They have contributed to the opening of foam cells and thus the decrease of density, which resulted in a decrease in brittleness (Table 8) and compressive strength (Table 6). FR was embedded in the structure of the C foam series and thereby reduced their brittleness compared to the brittleness of the CU foam series.to the foam causes a decrease in the softening point of modified foams by 18 \({}^{\circ}\)C in the C_0t series and 32 \({}^{\circ}\)C in the CU t series. The amount of cinnamon extract in the C_0t series foams practically did not affect the brittleness of foams, whereas for the CU_0t foams series, the CU_0t foam brittleness increase was observed in relation to the WU_0t foam, but its decrease with the increase of cinnamon-based filler content in the foam was observed; see Table 8. The reason for the CU_0t brittleness increase (in relation to for the CU_0t series) was lack of flame retardant in foams. There are many factors that determine the type of insulation and its thickness. For the insulation to be fully effective, it should meet at least the basic requirements, which include low absorbability and low water absorption from the environment [36]. Reduction of this parameters is very beneficial when these materials are using as thermal insulation. A lack of ability for water to accumulate in foams prevents a multiplication of mold and other microorganisms in the rooms where they are used [7; 8; 37]. In the investigated foams, an increase of water absorption (WA), absorbability (A) was observed with an increasing content of cinnamon extract in foams (Table 8). The increase in WA and W is due to the hydrophilic nature of the filler (cinnamon), which contains, among others, polyphenols (chlorogenic acid, flavonoids, and phenol acids); see Table 1. These compounds have hydrophilic -OH \begin{table}
\begin{tabular}{c c c c c c c} \hline
**Foam** & **A (\%)** & **WA (\%)** & **SP (\({}^{\circ}\)C)** & **B (\%)** & **d (kg/m\({}^{3}\))** & **CC (\%)** \\ \hline W & 12.33 \(\pm\) 0.37 & 5.15 \(\pm\) 0.05 & 184 \(\pm\) 5 & 13.27 \(\pm\) 0.01 & 39.67 \(\pm\) 0.03 & 83.2 \(\pm\) 0.2 \\ C5 & 13.41 \(\pm\) 0.40 & 5.67 \(\pm\) 0.06 & 189 \(\pm\) 6 & 14.34 \(\pm\) 0.01 & 39.60 \(\pm\) 0.03 & 74.3 \(\pm\) 0.2 \\ C10 & 22.34 \(\pm\) 0.67 & 6.14 \(\pm\) 0.06 & 181 \(\pm\) 5 & 13.04 \(\pm\) 0.01 & 35.72 \(\pm\) 0.02 & 39.1 \(\pm\) 0.1 \\ C15 & 36.05 \(\pm\) 1.08 & 9.64 \(\pm\) 0.10 & 166 \(\pm\) 5 & 11.93 \(\pm\) 0.01 & 33.97 \(\pm\) 0.02 & 5.7 \(\pm\) 0.0 \\ WU & 8.14 \(\pm\) 0.04 & 3.12 \(\pm\) 0.01 & 204 \(\pm\) 6 & 16.42 \(\pm\) 0.01 & 49.60 \(\pm\) 0.03 & 89.5 \(\pm\) 0.3 \\ CU5 & 23.22 \(\pm\) 0.69 & 3.78 \(\pm\) 0.01 & 185 \(\pm\) 6 & 45.60 \(\pm\) 0.31 & 30.94 \(\pm\) 0.02 & 17.4 \(\pm\) 0.5 \\ CU10 & 18.04 \(\pm\) 0.54 & 4.02 \(\pm\) 0.01 & 179 \(\pm\) 6 & 44.22 \(\pm\) 0.31 & 29.19 \(\pm\) 0.02 & 23.4 \(\pm\) 0.7 \\ CU15 & 17.14 \(\pm\) 0.51 & 4.99 \(\pm\) 0.02 & 172 \(\pm\) 6 & 42.13 \(\pm\) 0.29 & 29.43 \(\pm\) 0.02 & 28.1 \(\pm\) 0.8 \\ \hline \end{tabular}
\end{table}