## 3 Results  
### Quasi-Static Testing  
The complex geometry of the hybrid specimen does not allow the calculation of stress and strain. Therefore, in Figure 4a, the force-displacement diagram of two exemplary PPA-GF30 specimens can be seen at 23 \({}^{\circ}\)C and 60 \({}^{\circ}\)C, respectively. Comparing those two curves, both the slope and the maximum force are lower at 60 \({}^{\circ}\)C than at 23 \({}^{\circ}\)C. Both curves are rising steadily with a decreasing slope and show a typical behaviour for brittle polymers due to their viscoelastic properties. Furthermore, the displacement at rupture is slightly higher at 60 \({}^{\circ}\)C. An explanation is that polymers generally become softer the nearer they get to their glass transition temperature. The same observations can be made for the curves of the CFRP, and the same explanation as for PPA-GF30 could be applied to the CFRP specimens (see Figure 4b) because of their polymer epoxy matrix. The behaviour of the hybrid specimens is depicted in Figure 4c. For 23 \({}^{\circ}\)C, a dropdown in force occurs in rather short and drastic events, whereas at 60 \({}^{\circ}\)C, a smoother curve can be seen. As an explanation, different damage mechanisms in the hybrid specimen depending on the test temperature can be suggested. Displacement is significantly higher and also the area under the graph is bigger at 60 \({}^{\circ}\)C, which implies a higher energy absorption. Due to the generic specimen geometry, it was not possible to find a visual criterion when a specimen failed. Therefore, a threshold of 10% of the maximum force of the hybrid specimens was defined as failure criterion. Figure 3: Scheme of the experimental set-up. The increase in displacement at failure for the three shown force-displacement diagrams in Figure 4a-c leads to the assumption that the polymers, i.e., the PPA-GF30 and the epoxy matrix, soften at 60 \({}^{\circ}\)C. To verify these assumptions, the mean values of multiple equal specimens with their according error bars (standard deviation) are pictured in Figure 4d. Comparing them shows that this can only be verified for the hybrid specimens, which show a significant increase in maximum displacement. For PPA-GF30, the increase in displacement is slight but the CFRP specimens show no evident difference. However, the mean maximum force decreases from 23 \({}^{\circ}\)C towards 60 \({}^{\circ}\)C for PPA-GF30 and CFRP. This also contributes to the hypothesis of the softening. In Table 2, a brief comparative analysis is given for the PPA-GF30 and CFRP specimens at 23 \({}^{\circ}\)C and at 60 \({}^{\circ}\)C to emphasise those results. Due to the big error bars, there is no such comparison for the hybrid specimens. Error bars for PPA-GF30 and CFRP are very small, which shows that there is a high reproducibility. To obtain further information about the differences in damage mechanisms, a closer look is taken at the thermograms of the PPA-GF30 and the CFRP specimens. The thermograms in Figure 5 show the specimens right after cracking. The images are depicted in \(\Delta\)T \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Specimen** & \multicolumn{2}{c}{**Mean Maximum Displacement [mm]**} & \multicolumn{2}{c}{**Percentage Variance [\%]**} & \multicolumn{2}{c}{**Mean Maximum Force [KN]**} & \multicolumn{2}{c}{**Percentage Variance [\%]**} \\ \hline  & 23 \({}^{\circ}\)C & 60 \({}^{\circ}\)C & & 23 \({}^{\circ}\)C & 60 \({}^{\circ}\)C & \\ PPA-GF30 & 2.11 \(\pm\) 0.04 & 2.25 \(\pm\) 0.11 & 6.2 & 5.97 \(\pm\) 0.04 & 5.33 \(\pm\) 0.06 & 12 \\ CFRP & 1.00 \(\pm\) 0.38 & 1.00 \(\pm\) 0.06 & 0 & 5.55 \(\pm\) 0.11 & 5.17 \(\pm\) 0.13 & 6.8 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Comparative analysis of PPA-GF30 and CFRP specimens at the two different testing temperatures. Figure 4: Force-displacement curves of (**a**) PPA-GF30, (**b**) CFRP, (**c**) hybrid specimen, and (**d**) mean maximum values of force over displacement (very small error bars for PPA-GF30 and CFRP).