## 3 Results and Discussion
### Effect of Amount of TMS  
Figure 6 illustrates the surface morphology of rayon flock synthetic leather after TMS plasma treatment with different amounts of TMS. Figure 6a shows that sample with 0.1 mL TMS has a relatively smooth surface and a small number of rubs and burrs are deposited on it. The TMS deposited is insufficient for surface hydrophobicity improvement. The number of rubs and burrs on the plasma  
Figure 5: SEM micrographs illustrate the surface morphology of rayon flock synthetic leather after TMS plasma treatment with different treatment times: (**a**) 10 s, (**b**) 20 s, (**c**) 30 s, (**d**) 40 s (treatment parameters: amount of TMS = 0.2 mL; flow rate of helium = 12.5 LPM; jet distance = 10 mm; discharge power = 50 W).  
modified samples increases with amount of TMS applied, as shown in Figure 6b,c. After reaching the optimum amount of 0.2 mL TMS (Figure 6c), there is no further increase in deposition (Figure 6d).  
Table 3 shows the change of contact angle of rayon flock synthetic leather treated with different amount of TMS under the effect of plasma. It is noted that without the addition of TMS, no change in contact angle is seen when compared with the untreated sample. However, with an increasing amount of TMS, the contact angle increases, with an optimum at 0.2 mL. Further increase in TMS to 0.25 mL does not introduce further enhancement in the contact angle. When compared with Figure 6c,d, the deposition of TMS under the plasma treatment reaches a maximum at 0.2 mL TMS. Therefore, the contact angle results are supported by the surface morphological changes, with an increased amount of TMS deposited in the rayon flock synthetic leather surface.  
In order to have a better understanding of the surface hydrophobicity of rayon flock synthetic leather, the change in the sliding angle of rayon flock synthetic leather treated with different amounts of TMS under the effect of plasma is reported in Table 3. Generally speaking, the lower the sliding angle, the slicker the surface is. The slicker the surface, the less things like water and contaminants can stick and hence the better the hydrophobicity. As shown in Table 3, the sliding angle decreases with an  
Figure 6: SEM micrographs illustrate the surface morphology of rayon flock leather after TMS plasma treatment with different amounts of TMS: (**a**) 0.1 mL, (**b**) 0.15 mL, (**c**) 0.2 mL, (**d**) 0.25 mL (treatment parameters: treatment time = 30 s; flow rate of helium = 12.5 LPM; jet distance = 10 mm; discharge power = 50 W).  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Amount of** & **Untreated** &
\begin{tabular}{c} **0 (Treated With Helium** \\ **Plasma Only**) \\ \end{tabular} & **0.1** & **0.15** & **0.2** & **0.25** \\ \hline Contact angle (\({}^{\circ}\)) & 0 & 0 & \(47.4\pm 0.1\) & \(74.9\pm 0.2\) & \(135\pm 0.1\) & \(102.2\pm 0.2\) \\ Sliding angle (\({}^{\circ}\)) & 0 & 0 & \(72\pm 0.2\) & \(56\pm 0.2\) & \(32\pm 0.2\) & \(45\pm 0.3\) \\ \hline \hline \end{tabular}
\end{table}
Table 3: Effect of amount of TMS on contact angle (treatment parameters: treatment time = 30 s; flow rate of helium = 12.5 LPM; jet distance = 10 mm; discharge power = 50 W) (\(n=5\)).  
increasing amount of TMS and reaches an optimum at 0.2 mL. When 0.2 mL TMS is deposited on the rayon flock synthetic leather surface, the sample will have the highest contact angle value (135 \(\pm\) 0.1). Due to this high contact angle, the contact area between the water droplet and the rayon flock synthetic leather would be minimized and thus the water droplet can slide easily, leading to a low sliding angle.