## 3 Results and Analysis
### Controllable Preparation Result of the Shape Memory Hydrogenated Epoxy Resin (SM-HEP)
Figure 5: The second heating differential scanning calorimeter (DSC) curves of the shape-memory hydrogenated epoxy resin with inverse calculated formulations (heating flow = 10 \({}^{\circ}\)C/min). According to Table 2 and Figure 5, the preliminary fitted \(T_{\rm g}\) and measured \(T_{\rm g}\) were inconsistent, especially for the specimen JH-230 0.0274, for which the difference was 4.5 \({}^{\circ}\)C. To ensure the accuracy of the controllable preparation result, the SM-HEP values in Tables 1 and 2 were both used to linearly fit the relationship of the JH-230 content and \(T_{\rm g}\). The second linear fitting results are shown in Figure 6.  
As shown in Figure 6, the \(R^{2}\) of the second linear fitting results is 0.9462, and the second linear fitting equation of \(T_{\rm g}\) and the JH-230 content is shown in Equation (5). \[Y=-4.50489\times X+75.82575 \tag{5}\]  
With the same method, the corresponding back-calculated formulations of the \(T_{\rm g}\) values of 40, 45, 50, 55, 60 \({}^{\circ}\)C are shown in Table 3. The measured \(T_{\rm g}\) values tested by DSC are also displayed in Table 3.  
In Table 3, the linear fitted \(T_{\rm g}\) and measured \(T_{\rm g}\) are almost the same. The 45 degrees contour map was used to prove that the controllable preparation result was accurate. As can be seen in Figure 7, there is a high consistency between the fitted \(T_{\rm g}\) of the specimen obtained by the second linear fitting equation and the measured \(T_{\rm g}\) determined by the DSC. It was concluded that the second linear fit displays a good fitting precision and reproducibility. The \(T_{\rm g}\) is not a fixed value, but is variable in a certain range. Therefore, the preparation results obtained by the linear fit method are reasonable. In conclusion, the formulations of the SM-HEP-AM are shown in Table 3. \begin{table}
\begin{tabular}{l c c c c c c} \hline \hline \multirow{2}{*}{**Specimen**} & **AL-3040** & **JH-230** & **IPDA** & **Tg-Fitted** & **Tg-Measured (Uppercase)** & **Error Bars** \\  & **(mol)** & **(mol)** & **(mol)** & **(\({}^{\circ}\)C)** & **(\({}^{\circ}\)C)** & **(\({}^{\circ}\)C)** \\ \hline JH-230-0.0353 & 0.9647 & 0.0353 & 0.5 & 60 & 60.9 & 1.0 \\ JH-230-0.0463 & 0.9537 & 0.0463 & 0.5 & 55 & 55.5 & 0.7 \\ JH-230-0.0574 & 0.9426 & 0.0574 & 0.5 & 50 & 49.4 & 0.5 \\ JH-230-0.0685 & 0.9315 & 0.0685 & 0.5 & 45 & 44.8 & 0.4 \\ JH-230-0.0796 & 0.9204 & 0.0796 & 0.5 & 40 & 39.0 & 0.8 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Specimens with the second back-calculated formulations and their \(T_{\rm g}\) values. Figure 6: The second linear fitting relationship between the JH-230 content and the \(T_{\rm g}\). The Thermal Property of the Shape Memory Hydrogenated Epoxy Resin Used for Asphalt Mixtures (SM-HEP-AM)  
The DSC thermographs of the SM-HEP-AM are shown in Figure 8. The \(T_{\rm g}\) values obtained from the DSCanalysis are also marked in Figure 8. The results demonstrated that the JH-230 content in the SM-HEP-AM had a significant effect on the \(T_{\rm g}\). More specifically, the \(T_{\rm g}\) decreased with an increased JH-230 content in the SM-HEP-AM. \(T_{\rm g}\) is an essential transition temperature from the freezing to free-motion states of the segments in a polymer network. In the SM-HEP-AM network, the increased JH-230 content decreased the cross-link density and resulted in an increased mobility of the segments. Furthermore, the JH-230 molecular weight is 2500 g/mol and its flexibility is high. Therefore, the chain flexibility of the SM-HEP-AM network improved as the JH-230 content increased, leading to a decrease in \(T_{\rm g}\)[29]. The Molecular Structure of the Shape Memory Hydrogenated Epoxy Resin Used for Asphalt Mixtures (SM-HEP-AM)  
The chemical structures of the IPDA, JH-230, AL-3040, and SM-HEP-AM were confirmed through the FT-IR spectra in Figure 9. The absorption peak at 909 cm\({}^{-1}\) on the infrared spectra of the AL-3040  
Figure 8: The second heating DSC curves of the SM-HEP-AM (heating flow = 10 \({}^{\circ}\)C/min).