## 3 Results and Discussion
### Curing Reaction Mechanism for the Healing Agent
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**MC120D Fraction (\%)** & \(\frac{-\textbf{ln}(\beta/T_{P}\textbf{{}^{2}})-1000/T_{P}}{\textbf{Linear Fitting}}\) & **Relative Coefficient \(R^{2}\)** & **Activation Energy \(E\) (k) mol\({}^{-1}\))** & **Reaction Order \(n\)** \\ \hline \multirow{3}{*}{10} & y = \(-4.81416+6.36782x\) & 0.985 & \multirow{3}{*}{52.94} & \multirow{3}{*}{0.880} \\  & y = \(-18.96889+7.23911x\) & 0.989 & & \\ \hline \multirow{3}{*}{20} & y = \(-3.36634+5.61983x\) & 0.998 & \multirow{3}{*}{46.73} & \multirow{3}{*}{0.868} \\  & y = \(-17.4921+6.47836x\) & 0.998 & & \\ \hline \multirow{3}{*}{30} & y = \(-6.91955+6.99507x\) & 0.991 & \multirow{3}{*}{58.16} & \multirow{3}{*}{0.892} \\  & y = \(-21.00677+7.83769x\) & 0.993 & & \\ \hline \multirow{3}{*}{40} & y = \(-5.98578+6.53037x\) & 0.999 & \multirow{3}{*}{54.30} & \multirow{3}{*}{0.888} \\  & y = \(-20.03786+7.35817x\) & 0.999 & & \\ \hline \multirow{3}{*}{50} & y = \(-11.31952+8.65504x\) & 0.981 & \multirow{3}{*}{71.96} & \multirow{3}{*}{0.913} \\  & y = \(-25.37057+9.48248x\) & 0.984 & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Activation energy and reaction order with different mass fractions of the catalyst. The FTIR spectrum of diluent BGE is displayed in Figure 6B. The structure of BGE [35] is shown below. \[\mathrm{CH_{3}(CH_{2})}_{3}\mathrm{CH_{2}-CH-CH_{2}}\] \[\backslash\] /  
O  
The absorption peak at 1110 cm\({}^{-1}\) was generated by the stretching vibration of the linear fatty ether structure. The peaks at 913, 844, and 761 cm\({}^{-1}\) are the vibration absorptions of the epoxy ring. Among them, the peak at 913 cm\({}^{-1}\) is an end-epoxy type absorption peak. The change in these peaks can be used to determine the extent to which the ring opening reaction proceeds. Among the three absorption bands, the one at 844 cm\({}^{-1}\) has the strongest absorption and it is generated by the antisymmetric stretching vibration of the epoxy ring [36]. The FTIR spectra of the cured products of the epoxy resin are shown in Figure 7. The composition of the healing agent is as follows: MC120D content is 20% of the epoxy resin E-51 mass, and diluent BGE content is 12.5% (curve c in Figure 7A), 15% (curve d in Figure 7A), and 20% (curve e in Figure 7A) of the epoxy resin E-51 mass. The curing temperatures in Figure 7 encompass the first exothermic peak temperature range of the differential thermal profile of the epoxy resin in Figure 2. The FTIR curves of the different BGE contents reveal that the main characteristic absorption peaks of epoxy resin E-51 at 771 cm\({}^{-1}\), 1035 cm\({}^{-1}\), 1184 cm\({}^{-1}\), 1361 cm\({}^{-1}\), and 2928 cm\({}^{-1}\) disappeared, but the peak at 1607 cm\({}^{-1}\) did not change much. These results indicate that the heat resistance of the functional group is good, and it did not react at that temperature. Meanwhile, the epoxy spectra absorption peaks of BGE at 913, 844, and 761 cm\({}^{-1}\) also disappeared, which demonstrated that the epoxy ring fully participated in the curing reaction [37]. The data presented in Figure 7B show that the strength at 3482 cm\({}^{-1}\) increases with the increase in the BGE content, which indicates that the polymerization reaction produces new hydroxyls. The FTIR spectra of the same samples as those shown in Figure 7 are displayed in Figure 8. However, the temperature was raised to 270 \({}^{\circ}\)C, which encompasses the temperature range of the second exothermic peak of the differential thermal curves shown in Figure 2 for the epoxy resin curing reaction. The spectra reveal that the changes for the main characteristic peaks of the epoxy resin E-51 and BGE are similar to those that are presented in Figure 7. In Figure 7B, the red, blue and pink represent b(E-51 + 12.5%BGE), c(E-51 + 15%BGE), and d(E-51 + 20%BGE), respectively. Figure 6: Fourier-transform infrared spectroscopy (FTIR) spectra of the healing agent. (**A**) the epoxy resin E-51; (**B**) the diluent BGE.