## 3 Results and Discussion
### Microstructure and Thermal Conductivity  
It is common to find that incorporating various fillers can affect the density of the foam due to the interference of the solid particles with the polymer and foaming kinetics. The density results are summarized in Table 3. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**PUR Foam**} & \multicolumn{4}{c}{**Parameter**} \\ \cline{2-5}  & **Apparent Density,** & **Closed Cell Content,** & & \\
**Composite** & **kg/m3** & **vol.\%** & & \\ \hline Control PUR & 43.7 \(\pm\) 4 & 94.4 \(\pm\) 0.52 & 1.32 \(\pm\) 0.12 & 177 \(\pm\) 5 \\ PUR/Per-2.5 & 44.5 \(\pm\) 3 & 94.9 \(\pm\) 0.63 & 0.812 \(\pm\) 0.11 & 100 \(\pm\) 4 \\ PUR/Per-5 & 47.4 \(\pm\) 5 & 95.4 \(\pm\) 0.55 & 0.618 \(\pm\) 0.12 & 88.6 \(\pm\) 6 \\ PUR/Per-7.5 & 47.6 \(\pm\) 2 & 97.3 \(\pm\) 0.42 & 0.725 \(\pm\) 0.10 & 74.5 \(\pm\) 6 \\ PUR/Per-10 & 47.4 \(\pm\) 3 & 94.6 \(\pm\) 0.44 & 0.837 \(\pm\) 0.16 & 65.5 \(\pm\) 2 \\ PUR/Verm-2.5 & 45.7 \(\pm\) 5 & 94.0 \(\pm\) 0.22 & 0.882 \(\pm\) 0.14 & 76.7 \(\pm\) 6 \\ PUR/Verm-5 & 44.9 \(\pm\) 4 & 91.4 \(\pm\) 0.26 & 0.703 \(\pm\) 0.19 & 71.6 \(\pm\) 4 \\ PUR/Verm-7.5 & 46.8 \(\pm\) 3 & 91.6 \(\pm\) 0.38 & 0.754 \(\pm\) 0.13 & 65.3 \(\pm\) 3 \\ PUR/Verm-10 & 52.3 \(\pm\) 2 & 91.2 \(\pm\) 0.44 & 0.772 \(\pm\) 0.12 & 62.7 \(\pm\) 5 \\ PUR/PerDex-2.5 & 49.4 \(\pm\) 4 & 97.6 \(\pm\) 0.62 & 1.12 \(\pm\) 0.22 & 138 \(\pm\) 6 \\ PUR/PerDex-5 & 52.3 \(\pm\) 5 & 97.3 \(\pm\) 0.51 & 0.780 \(\pm\) 0.14 & 155 \(\pm\) 4 \\ PUR/PerDex-7.5 & 56.4 \(\pm\) 5 & 97.9 \(\pm\) 0.38 & 0.623 \(\pm\) 0.16 & 168 \(\pm\) 3 \\ PUR/PerDex-10 & 63.7 \(\pm\) 4 & 97.0 \(\pm\) 0.49 & 0.592 \(\pm\) 0.12 & 185 \(\pm\) 6 \\ PUR/VermDex-2.5 & 48.0 \(\pm\) 3 & 96.1 \(\pm\) 0.29 & 1.01 \(\pm\) 0.23 & 113 \(\pm\) 4 \\ PUR/VermDex-5 & 51.0 \(\pm\) 2 & 98.0 \(\pm\) 0.49 & 0.795 \(\pm\) 0.14 & 115 \(\pm\) 3 \\ PUR/VermDex-7.5 & 56.4 \(\pm\) 3 & 94.4 \(\pm\) 0.64 & 0.832 \(\pm\) 0.16 & 119 \(\pm\) 4 \\ PUR/VermDex-10 & 59.8 \(\pm\) 2 & 94.2 \(\pm\) 0.58 & 0.865 \(\pm\) 0.17 & 119 \(\pm\) 3 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Structural parameters of PUR foam composites. They confirm that the parameter increase depends on the increase in filler concentration and agree with the results reported in the study by [PERSON] et al. [58]. In this case, the apparent density of PUR/Per foam composites increased by a maximum of 9%, whereas for PUR/Verm foam composites, the parameter reached its highest value at 10 wt.% Verm addition. It is also worth noting that Dex-activated Per and Verm particles caused an even greater increase in the apparent density of PUR foam composites. For instance, the highest increase was 46% for PUR/PerDex foam composites and 37% for PUR/VermDex foam composites. The apparent densities of Dex-activated and non-activated particles-filled PUR foam composites could be attributed to differences in the bulk densities of the fillers. To evaluate the impact of non-activated and Dex-activated Per and Verm particles on the thermal conductivity of PUR foam composites, graphs were presented based on the concentration of each filler added (Figure 4). It can be seen from Figure 4a-d that the difference in thermal conductivity between the PUR/Per, PUR/Verm, PUR/PerDex, and PUR/VermDex foam composites was insignificant. However, a 3-4% reduction in the parameter can be observed, i.e., from 0.0295 W/(m\(\cdot\)K) to 0.0283 W/(m\(\cdot\)K) for 2.5 wt.% filler addition (Figure 4a), to 0.0284 W/(m\(\cdot\)K) for 5 wt.% willer addition (Figure 4b) and to 0.0285 W/(m\(\cdot\)K) for 7.5 wt.% filler addition compared to control PUR foam. The cell size results in Table 2 can explain this. A closer examination of the results in Table 3 and Figure 5 revealed that all fillers (Per, Verm, PerDex, VermDex) and their concentrations (2.5-10 wt.%) reduced average cell size by a minimum of 15% and by a maximum of 55% compared to control PUR foam indicating that the filler particles act as nucleating agents. Similar observations were made by [PERSON] et al.