## 3 Results and Discussion
### Effects of Immersion Durations on Tensile Strength  
The effects of immersion periods in neutral, acid, and alkaline solutions on the tensile strength of recycled Kevlar(r)/PET/LPET nonwoven geotextiles are examined. Figures 1 and 2 indicate the tensile strength of nonwoven geotextiles that are immersed in water for different periods. Thus, the tensile strength of nonwoven geotextiles does not significantly fluctuate as a result of the immersion temperatures, or of the sample types that are taken along CD or MD. Furthermore, \(p>0.05\) in one-way ANOVA analysis also indicates the differences in tensile strength are not statistically significant, indicating that the tensile strength of nonwoven fabrics is not influenced by being in a neutral environment for 4 months. Figures 3 and 4 indicate the tensile strength of nonwoven geotextiles that are immersed in a strong acid solution for 1, 2, 3, or 4 months (_i.e._, the experimental group). The control group is the nonwoven geotextiles without immersion. Table 3 indicates the tensile strength of samples that are immersed in CH3 COOH in four months. With an acid solution at 23 \({}^{\circ}\)C, the nonwoven geotextiles without Kevlar(r) fibers have a tensile strength that is in inversely proportion to the immersion periods (1, 2, 3, and 4 months), while the nonwoven geotextiles containing 5, 10, 15, or 20 wt. % Kevlar(r) fibers exhibit comparable tensile strength regardless of the immersion periods. However, this trend is not observed for nonwoven fabrics that are immersed in an acid solution at 50 \({}^{\circ}\)C, and the tensile strength slightly decreases as a result of the increasing immersion period. These differences in tensile strength of the control group and the experimental group are then further analyzed using statistical analyses. The one-way ANOVA analysis indicates that the 0/80/20 exhibits a statistically significant difference (\(p<0.05\)) in tensile strength of nonwoven geotextiles that are immersed in an acid solution at 23 \({}^{\circ}\)C.  
Figure 1: Tensile strength and weight along the (**a**) cross machine direction (CD) and (**b**) machine direction (MD) of recycled Kevlar(r)/PET/LPET nonwoven geotextiles that are immersed in H\({}_{2}\)O at 23 \({}^{\circ}\)C for 4 months. Figure 2: Tensile strength and weight along the (**a**) CD and (**b**) MD of recycled Kevlar®/PET/LPET nonwoven geotextiles that are immersed in H\({}_{2}\)O at 50 \({}^{\circ}\)C for 4 months. Furthermore, when the immersion periods are considered, the post hoc [PERSON]'s test indicates that the significance in the 0/80/20 is ranked as 4 < 0, 1, 2, 3 (months). Namely, a 4-month immersion in an acid solution statistically significant debilitates the tensile strength of the control group, in comparison with a 0-, 1-, 2-, or 3-month immersion. In contrast, the content of Kevlar(r) fibers of being 10, 15, or 20 wt. % is \(p\) > 0.05. This shows the experimental group is acid resistant. In addition, when the experimental group is immersed in an acid solution at 50 \({}^{\circ}\)C, the one-way ANOVA analysis shows statistically significant differences in its acid resistance. This result suggests that the experimental group fails at remaining at its original tensile strength under an acid environment at a high temperature, which confirms to the results of the study conducted by [PERSON] _et al._[17]. Figures 5 and 6 show the tensile strength of the recycled Kevlar(r)/PET/LPET nonwoven geotextiles (experimental group) that are immersed in an alkali solution for 1, 2, 3, and 4 months. Regardless of the immersion temperatures of 23 \({}^{\circ}\)C or 50 \({}^{\circ}\)C, and regardless of the fact that samples are taken along the MD or along the CD, a 1-month immersion results in a significant decrease in the tensile strength of the experimental group. Although it is least possible for geotextiles to be used in an