## 3 Analysis of Test Results
### Analysis of Flowability Test Results  
To analyze the flowability of ceramic polymer composites, MI measurement and a spiral flow (SF) experiment were performed. Table 4 lists the MI measurements and the SF experiment results, and Figure 1 shows the specimens injected by the SF experiment.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameters of Compounding Process** & **Melt Flow Rates (g/10 min)** & **Spiral Length (mm)** \\ \hline PBT (0) & 80 & 440 \\ PBT (60) & 68.5 & 400 \\ PA6 (0) & 63.0 & 385 \\ PA6 (50) & 50.4 & 340 \\ PA6 (60) & 46.2 & 315 \\ PA6 (70) & 36.0 & 297 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Flow characteristics of PA6/PBT/Al\({}_{2}\)O\({}_{3}\) composites with different weight ratios.  
Figure 1: Spiral lengths of the PBT and PA6 compounds according to the Al\({}_{2}\)O\({}_{3}\) content (**a**) PBT (0): 440 mm, (**b**) PBT (60): 400 mm, (**c**) PA6 (0): 385 mm, (**d**) PA6 (50): 340 mm, (**e**) PA6 (60): 315 mm, (**f**) PA6 (70): 297 mm.  
As shown in Table 4, when 60% alumina was added to PBT, the spiral length decreased by 40 mm compared to PBT without alumina. The MI measurement also decreased from 80 to 68.5 g/10 min. For PBT, the experiment was attempted based on the alumina content, but the experiment could not be performed properly as the specimens showed a tendency to be damaged because of cooling shrinkage after the SF experiment.  
For PA6, the spiral length decreased as the alumina content increased. When 70% alumina was added, the spiral length decreased by 88 mm compared to PA6 (0), confirming that the flowability significantly decreased. The spiral length of PA6 (0) was 385 mm and that of PA6 (50) was 340 mm; this was calculated as a 12% reduction in the spiral length. In the case of PA6 (60), the injection rate was 315 mm and the reduction rate was 7.4% when PA6 (50) was selected as the basis of comparison. In the case of PA6 (70), the reduction rate was 5.7% when based on PA6 (60). This implies that the reduction rate is not proportional to the alumina content. Compared to the initial 50% addition of alumina, additions of 10% and 50% or more had a greater effect on flowability as compared to the reduction of spiral length. Moreover, when PBT (60) and PA6 (60) were compared, PBT exhibited better flowability than PA6 (60); however, the specimen of PBT was damaged during cooling and subjected to nozzle clogging. In the case of PBT (60), the flow characteristics decreased by 9.1% when compared to PBT; in the case of PA6 (60), this decrease was 18.2% when compared to PA6 (0). The effect on flow due to the addition of alumina was confirmed to have a more profound influence on PA6 than on PBT.  
Based on the results of the thermal conductivity test and SF experiment, samples were injected by adding 60% alumina to PBT and PA6, respectively. Figure 2 shows the injection results of PBT (60) and PA6 (60). When injection was performed using a rectangular mold with round edges and a constant thickness, the PBT sample showed surface breakage while being cooled after injection. This appears to be because the resin of PBT was brittle. The PA6 sample did not exhibit any breakage. The experimental results provided by the MI, spiral test, and the square injection methods confirmed that the PA6 (60) did not possess suitable flowability characteristics when compared to the conventional PA6. However, there was no problem in injecting the shape, and the possibility of an additional reflector injection was confirmed.