## 3 Results and Discussion  
### Effects of Fiber Ratios on Tensile Strength  
Table 2 shows the contents of Kevlar(r) fibers of recycled Kevlar(r)/PET/LPET nonwoven geotextiles. The geotextiles without immersion in any solutions have a tensile strength that is proportional to the content of recycled Kevlar(r) fibers. In comparison to the control group containing zero Kevlar(r) fibers, the experimental groups containing 15 wt. %-20 wt. % of Kevlar(r) fibers exhibit statistically significant differences at (\(F\) (4, 20) = 5.201, \(p<0.05\)). In addition, PET fibers have a lower alkali resistance, and therefore, one-way ANOVA and post hoc [PERSON]'s tests are performed on the recycled Kevlar(r)/PET/LPET nonwoven geotextiles in order to determine the influence of Kevlar(r) contents on their tensile strength. According to one-way ANOVA, the differences are statistically significant (\(p<0.05\)) among different contents of recycled Kevlar(r) fibers, indicating that the contents of Kevlar(r) pertain to tensile strength. Next, [PERSON]'s test is used to analyze the differences in tensile strength among nonwoven geotextiles containing various contents of Kevlar(r) fibers that are immersed \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Solutions** & **Chemical** & **Solution** & **pH** & **Temperature** & **Immersion Period** \\  & **Formula** & **Concentration** & **pH** & **(°C)** & **(Months)** \\ \hline Acetic acid & CH\({}_{3}\)COOH & 5\% & 3 & & \\ Sodium hydroxide & NaOH & 10\% & 13 & 23, 50 & 1, 2, 3, 4 \\ Deionized water & H\({}_{2}\)O & - & 6 & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The immersion conditions on the tensile strength of recycled Kevlar®/polyester/ low-melting-point polyester (recycled Kevlar®/PET/LPET) nonwoven geotextile. in NaOH, in terms of combinations of immersion temperatures of 23 \({}^{\circ}\)C (\(T_{1}\)) and 50 \({}^{\circ}\)C (\(T_{2}\)) and immersion periods of 1, 2 and 3 months (hereafter \(P_{1}\), \(P_{2}\), and \(P_{3}\)). The analyses indicate that in comparison of the four combinations of \(T_{1}P_{1}\), \(T_{1}P_{2}\), \(T_{1}P_{3}\), and \(T_{2}P_{1}\), the experimental groups (_i.e._, nonwoven geotextiles containing 5 wt. %-20 wt. % Kevlar(r) fibers) have a statistically significant higher tensile strength than the control group (_i.e._, nonwoven geotextiles without Kevlar(r) fibers). According to [PERSON]'s analysis, there are statistically significant differences in the tensile strength among nonwoven geotextiles with immersion conditions of \(T_{1}P_{2}\), \(T_{1}P_{3}\), and \(T_{2}P_{1}\). The tensile strength of nonwoven geotextiles is ranked according to the content of Kevlar(r) fibers as 20, 15 wt. % > 10, 5 wt. % > 0 wt. % (\(T_{1}P_{2}\)), 20, 15, 10 wt. % > 5 wt. % > 0 wt. % (\(T_{1}P_{3}\)), and 20, 15 wt. % > 10, 5 wt. % > 0 wt. % (\(T_{2}P_{1}\)). Such results are ascribed to Kevlar(r) fibers that have a high modulus and high strength. The molecular chains of Kevlar(r) fibers have a benzene structure, and their molecular bonding has high compactness and stiffness. A value of 15 wt. % or 20 wt. % of Kevlar(r) fibers can effectively improve the tensile strength of nonwoven geotextiles. In addition, the majority of the fibers are arranged along the CD during the nonwoven process, and thus tensile strength along the CD is greater than that along the MD.