# Characterizing the Tensile Behaviour of Woven and Composite Fabrics under UV Exposure
## 5 Conclusions  
Prolonged exposure of woven geotextile to UV radiation revealed the greatest extent of degradation through minimum tensile strength and retained strain percentages of 69.55% and 80.74%, respectively, after five-months of outdoor exposure. The woven geotextile showed a more brittle behaviour under prolonged UV exposure. SEM micrographs of woven fabrics revealed considerable loosening in fibre structures that were originally densely packed and well-aligned. Disruption of fibre-to-fibre interactions and alignment most likely contributed to the tensile property degradation. Such evidence was further supported by the FT-IR analysis, which revealed a chemical structure change of the polypropylene after the outdoor weathering test via the formation of acetic acids as a by-product, which was seen in the absorbance peak created at a wavenumber of 1713 cm\({}^{-1}\). The formation of an absorbance peak became notable for its extended period of UV exposure. Surface micrographs of composite fabrics indicated significant microcracks with increased dimension following prolonged UV exposure. These observed microcracks on the non-woven geotextile, however, did not significantly contribute towards the loss of tensile properties. On the other hand, FTIR analysis detected that no chemical structure alteration occurred in the polymer matrix after five months of UV exposure. This suggested that the non-woven geotextiles acted as a sacrificial layer and protected the underlying primary load-bearing woven fabrics from rapid degradation. Therefore, the additional layers of non-woven geotextile successfully proved their effectiveness in protecting the woven fabrics from being used alone. As a matter of fact, the short study period of five months adopted in this study was insufficient to adequately evaluate the tensile behaviour of composite fabrics under UV exposure. Accordingly, in future studies, it is recommended that the outdoor UV weathering test be extended until the half-life (i.e., 50% retained) of the tensile properties is achieved. Moreover, it is recommended that the deposition of dust and microscopic dirt particles in the polymer matrix that potentially affected the tensile behaviour of composite fabrics under prolonged outdoor UV weathering be investigated. Overall, this study provides clear evidence on the UV degradation of engineered fabrics in outdoor UV weathering tests, which greatly supports the earlier hypothesis \begin{table}
\begin{tabular}{c c c} \hline \hline
**Wavenumber (cm\({}^{-1}\))** & **Vibration** & **Assignment** \\ \hline
2955, 2952, 2949 & Asymmetrical stretching & \(CH_{3}\) \\
2916 & Asymmetrical stretching & \(CH_{2}\) \\
2867 & Stretching & \(CH_{3}\) \\
2838 & Symmetrical stretching & \(CH_{2}\) \\
1456 & Symmetrical bending & \(CH_{2}\) \\
1436 & Bending & \(CH_{2}\) \\
1375 & Symmetrical bending & \(CH_{3}\) \\
997, 972 & Rocking, stretching & \(CH_{3}\), C-C \\
840 & Rocking & C-H \\
809 & Stretching & C-C \\ \hline \hline \end{tabular}
\end{table} 
Table 3: FTIR absorption bands of polypropylene. made that the degradation of engineered fabrics will exacerbate with prolonged UV exposure. Laboratory experimental tests from this study also indicated a close agreement in supporting engineered fabric degradation. Conceptualization, S.Y.J. and V.A. ; methodology, S.Y.J. ; software, S.Y.J. ; validation, S.Y.J. ; formal analysis, S.Y.J. ; investigation, S.Y.J. ; resources, V.A. ; data curation, S.Y.J. ; writing--original draft preparation, S.Y.J., L.Z.H. and S.C.P. ; writing--review and editing, S.Y.J., L.Z.H. and V.A. ; supervision, V.A. ; project administration, V.A. ; funding acquisition, V.A. and S.C.P. All authors have read and agreed to the published version of the manuscript. This research was funded by Tencate Geosynthetics Asia Sdn Bhd grant number CNI-000115, and Tencate Geosynthetics Asia Sdn Bhd partially finances the APC. Not applicable.