## 3 Results and Discussions
### Shape Memory Property Analysis  
Through the DMA analysis, it can found that the SiCw has a passive effect on the shape fixity ratio. However, because the SiCw does not have shape memory behavior, there is no doubt that the SiCw has a negative effect on the shape recovery ratio of the SiCw/hydro-epoxy composite. In order to analyze the effect of SiCw content on the shape memory properties of the hydro-epoxy system, we tested the shape memory performance of the SiCw/hydro-epoxy composite. The results are shown in Table 1, revealing that, with the increase in SiCw content in the shape memory composites, the shape recovery speed slightly decreased, the shape fixity ratio improved, and the shape recovery ratio significantly decreased. However, the shape recovery ratio of all samples was more than 95%, which indicates that the SiCw/hydro-epoxy composite is an excellent shape memory polymer composite. Figure 8 shows the shape memory process of a specimen with 8 wt % SiCw. Starting from the original shape, the specimen is deformed into a U shape in the oven. Upon cooling under load, the deformed temporary shape is fixed. Then, placing the specimen in the 56 \({}^{\circ}\)C oven, full recovery was observed after only 75 s.  
Figure 7: SEM of the SiCw/hydro-epoxy composites. In fact, the shape memory effect of the polymer composite is determined by two factors. One is the external condition [32]. These external conditions include the deformation amplitude, the velocity of deformation, deformation temperature, temporary fixed time, cooling rate, and deformation response times. Different conditions cause different shape memory effects. The other is the structure of the polymer composite [33]. Therefore, it is very important to control the external conditions of the shape memory polymer composites when the polymer has the same structures. In this work, we mainly analyzed the effect of the deformation temperature and cycle times on the shape memory performance of the SiCw/hydro-epoxy composites. The sample with 12 wt % SiCw was used to investigate the effect of the deformation temperature on the shape memory effect of the SiCw/hydro-epoxy composite, as shown in Figure 9. According to the results, the slope of the curves is generally larger from 60\({}^{\circ}\) to 120\({}^{\circ}\). This indicates that the shape recovery rate is high. However, the specimens have a relative low recovery rate at the initial and final stages. This increase is because, during the initial stage, the specimen needs time to increase temperature to that of the shape memory transition. The molecular chain slowly begins to creep, and the frozen stress begins to release gradually. After that, the frozen stress releases rapidly, and the shape recovery speed significantly increases. However, during the final stage, there is little frozen stress in the specimen, and the recovery rate thus becomes slow again. Figure 10 shows the effect of the cycling number on the recovery ratio of SiCw/hydro-epoxy composites. It can be found that the shape recovery ratio of composites slightly decreases with increasing cycling number. However, the shape recovery ratio was gradually balanced when the cycling number was higher than 5. This phenomenon is attributed to the accumulation of plastic deformations in the composites, which inevitably occurs during the recovery process. Moreover, when the deformation occurs more than 5 times, the change in the shape recovery ratio is small, which is due to the stability of the molecular chain and plastic deformations. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Sample** & **Bulk** & **4 wt \%** & **8 wt \%** & **12 wt \%** & **16 wt \%** \\ \hline \(\text{Vr}^{\circ}/\text{s}\) & 3.21 & 2.65 & 2.4 & 2.07 & 1.82 \\ \(R_{\text{f}}/\%\) & 98.5 & 99.3 & 99.8 & 100 & 100 \\ \(R_{\text{r}}/\%\) & 99.7 & 99.2 & 98.4 & 97.6 & 95.7 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Effect of SiCw content on the shape memory properties of the hydro-epoxy system.