## 3 Results and Discussions
### Dynamical Mechanical Analysis (DMA)  
The materials' properties, such as the storage modulus (\(E\)'), loss modulus (\(E\)'') and the damping factor (tan \(\delta\)) of the ELO-based resin and composites, were studied by DMA (Figure 5). From the thermomechanical data given in Table 2, we can see that both the nature and the quantity of the filler influence the materials' behaviour. Considering the glassy region of the storage modulus, the addition of 1 and 5 wt.% HC led to a substantial decrease of the \(E^{\prime}\) value, but starting with the material with 10 wt.% HC in its composition, the \(E^{\prime}\) modulus increases considerably with the hydrochar amount. Therefore, when HC is in small quantities in the formulation composition, it fully participates in the copolymerization process, generating new polymeric structures. As the amount of hydrochar increases, the system becomes supersaturated, and the particles that have not chemically interacted act as filler, giving rigidity to the material. In the case of SB-based systems, the storage modulus in the glassy state increases significantly compared to the resin, but its value is influenced by the filler amount. For the materials with 1-10 wt.% SB, the \(E^{\prime}\) value is doubled and even tripled compared with the resin, and then it decreases suddenly starting with the materials filled with 15 wt.% spruce bark powder. This decrease may be due to the agglomeration of wood particles in the polymeric matrix, which may \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & **Density** & \(T_{\text{g-DS}}\) & \(T_{\text{5\%}}\) & \(T_{\text{5\%}}\) & **Tan \(\delta\)** & **Tan \(\delta\) Peak** & \(E\) at 25 \({}^{\circ}\)C & \(E\) at 150 \({}^{\circ}\)C & \(v\) & \(Mc\) & **Hardness Test** \\  & **(g/cm\({}^{3}\))** & **(\({}^{\circ}\)C)** & **(\({}^{\circ}\)C)** & **Height** & **(MPa)** & **(MPa)** & **(mmol\(\cdot\)cm\({}^{-3}\))** & **(g/mol)** & **(Shore D)** \\ \hline EDI & 0.9456 & 45 & 282 & 42 & 0.63 & 242 & 11 & 0.93 & 930 & 63 \\ \hline EDI99\_HC1 & 1.2627 & 43 & 274 & 24 & 0.61 & 58 & 11 & 1.14 & 1255 & 65 \\ \hline EDI95\_HC5 & 1.1317 & 31 & 291 & 29 & 0.58 & 98 & 13 & 1.11 & 946 & 75 \\ \hline EDI90\_HC10 & 1.1401 & 38 & 280 & 36 & 0.58 & 260 & 17 & 1.03 & 697 & 80 \\ \hline EDI85\_HC15 & 1.1745 & 35 & 271 & 43 & 0.54 & 560 & 26 & 0.88 & 694 & 81 \\ \hline EDI80\_HC20 & 1.1174 & 37 & 273 & 45 & 0.53 & 727 & 40 & 0.23 & 290 & 85 \\ \hline EDI70\_HC30 & 1.0528 & 33 & 262 & 43 & 0.47 & 911 & 68 & 0.22 & 161 & 84 \\ \hline EDI99\_SB1 & 1.2901 & 31 & 274 & 49 & 0.77 & 700 & 11 & 1.15 & 1123 & 64 \\ \hline EDI95\_SB5 & 1.0331 & 31 & 263 & 47 & 0.89 & 790 & 11 & 1.10 & 938 & 75 \\ \hline EDI90\_SB10 & 1.1288 & 30 & 261 & 42 & 0.91 & 850 & 10 & 1.02 & 1100 & 77 \\ \hline EDI85\_SB15 & 1.1571 & 27 & 221 & 40 & 1.15 & 550 & 9 & 0.87 & 1330 & 84 \\ \hline EDI80\_SB20 & 1.0284 & 25 & 218 & 37 & 1.22 & 330 & 2 & 0.24 & 4432 & 80 \\ \hline EDI70\_SB30 & 1.0192 & 20 & 192 & 40 & 1.22 & 545 & 2 & 0.23 & 4464 & 84 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Physico-chemical and thermo-mechanical properties of the samples. lead to a steric hindrance, blocking some sites from forming new chemical bonds. This result corroborates the calculated crosslink densities (Table 2) that increase from 1 to 10% of filler ratio, and thereafter, in both cases the values decrease. The storage modulus at room temperature for the ELO-based matrix is about 242 MPa, while in the case of the HTC-based system, the highest \(E^{\prime}\) value is reached by the formulation with 30 wt.% HC (\(\sim\)911 MPa), and for the SB-based systems, the maximum is reached by the formulation filled with 10 wt.% SB (\(\sim\)850 MPa). The storage modulus in the rubbery plateau of the designed polymeric systems was also analysed. For HC-based materials, the addition of filler increased \(E^{\prime}\) in the rubber region, improving the stiffness of the formulations, so HC has a reinforcement effect.