## 3 Results and Discussion
### The Effects of Superhydrophobic Treatment on TG, DSC and Fabric Burnt Length  
Figure 7a-c and Table 3 show that the samples before and after the hydrophobic treatment did not destroy the flame retardant property of the PSA. As for PSA-SS-W1, the thermo-gravimetric process of the PSA fiber can be divided into two stages. In the first stage, the weight loss ratio is small because it is caused by the evaporation of the residual solvent and small-molecule auxiliaries. In the second stage, the weight loss rate is high because of the decomposition of the PSA fiber. Specifically, the heat loss rate of the PSA fiber reaches the maximum at 450.8 \({}^{\circ}\)C, which is generally defined as its thermal decomposition temperature. With the temperature increasing to 800 \({}^{\circ}\)C, the residue accounts for 50.67%, with half of the material not being decomposed. When it comes to the superhydrophobic-treated PSA-SS-W1', the surface is covered by waterproof 2P that consists of more water and small molecules. They undergo a volatile cracking process continuously with the rising temperature and thus the residue is only 29.74 % at 800 \({}^{\circ}\)C. However, PSA-SS-W1' has a thermal decomposition temperature of 454.0 \({}^{\circ}\)C, which is comparable to that of PSA-SS-W1, because the PSA fiber starts to decompose at this specified temperature. Usually, materials with a high thermal decomposition temperature have a better thermal  
Figure 6: The influence of different wire content fabrics on the (**a**) permittivity’s real part (\(\varepsilon^{\prime}\)); (**b**) permittivity’s imaginary part (\(\varepsilon\"\)) and (**c**) loss tangent (tan\(\theta\)). stability. Moreover, the high residue content at the termination of the temperature indicates that there is less combustible gas. The residue has a relatively higher heat absorption, which leads to a decrease in heat energy released by the burning material. Subsequently, it is difficult to render fibers with thermal cracking, which prevents the combustion of materials and improves the combustion resistance and refractory [36; 37; 38]. Therefore, PSA roving has a good refractory and is proven to be an effective material in this study. Based on the DSC curves, the employment of superhydrophobic treatment does not affect the melting peaks. The DSC curves fluctuate significantly at 400-450 \({}^{\circ}\)C, which means that the fibers undergo a drastic reaction equivalently. Meanwhile, no carbonized phenomenon occurred, indicating that within this temperature range, thermal cracking occurs to the fibers. Moreover, the burned length of fabrics is dependent on the density, porosity, and structure of the fabrics. To minimize the error, each sample processed with superhydrophobic treatment is used to compare the length before and after combustion. Figure 7d shows that the flame-retardant property of fabrics does not compromise for the employment of superhydrophobic treatment. The burned length of PSA-SS-1, PSA-SS-2, PSA-SS-W1, and PSA-SS-W2 is 33.0 mm, 34.5 mm, 37.5 mm, and 36 mm, which is 1 mm, 3 mm, 4 mm, and 3 mm longer than the original length, respectively. The average burned length of samples is shorter than 40 mm. The fabrics do not demonstrate distinct shrinkage, cracking, and dripping during the combustion, after which the fabrics exhibit carbonization and have a crisp edge, retaining good fabric \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sample** & **T \({}_{\text{swt}}\)\%** (\({}^{\circ}\)C) & **T\({}_{\text{max1}}\)** (\({}^{\circ}\)C) & **T\({}_{\text{max2}}\)** (\({}^{\circ}\)C) & **Resolute at 800 \({}^{\circ}\)C(\%)** \\ \hline PSA-SS-W1 & 435.4 & 450.8 & 519.4 & 50.67 \\ PSA-SS-W1\({}^{\prime}\) & 210.6 & 454.0 & 510.9 & 29.74 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The thermogravimetric analysis (TG) and differential thermogravimetry analysis (DTG) data of fabrics under a nitrogen atmosphere as related to the employment of hydrophobic treatment.