# Mechanical Performance of Polymer Materials for Low-Temperature Applications
## 4 Conclusions  
In the present study, the strain rates and temperature dependencies of PVDF, PE, and ABS were analyzed, and the mechanical responses of these materials were compared to provide a quantitative index for selecting industrial pipe materials at low temperatures. The significant findings of this study are as follows:  
* As temperature decreased, the tensile strength and Young's modulus of the tested polymers increased. However, the fracture strain and toughness markedly decreased in the cryogenic conditions. Hence, the effects of temperature variation on the durability of polymer materials should be investigated for industrial applications. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Temp.** & \multicolumn{2}{c}{**PVDF**} & \multicolumn{2}{c}{**PE**} & \multicolumn{2}{c}{**ABS**} \\ \cline{2-7} (\({}^{\circ}\)**C)** & \(\epsilon_{\text{F}}\) & **ut (MPa)** & \(\epsilon_{\text{F}}\) & **ut (MPa)** & \(\epsilon_{\text{F}}\) & **ut (MPa)** \\ \hline \(-100\) & 0.024 (1.94) & 22.30 (1.52) & 0.066 (1.62) & 30.00 (1.60) & 0.025 (2.55) & 11.35 (2.33) \\ \hline \(-50\) & 0.070 (1.34) & 54.54 (1.24) & 0.093 (1.42) & 30.72 (1.48) & 0.041 (1.43) & 17.92 (2.37) \\ \hline \(0\) & 0.173 (1.62) & 92.52 (1.34) & 0.197 (1.34) & 50.24 (1.29) & 0.043 (1.35) & 15.30 (1.36) \\ \hline \(25\) & 0.277 (1.22) & 118.8 (1.38) & 0.273 (1.32) & 40.08 (1.28) & 0.053 (1.30) & 16.02 (1.32) \\ \hline \hline \end{tabular} Note: Values in parentheses (\(0\)) represent standard deviation.  
\end{table} 
Table 3: Fracture strain and modulus of toughness from temperature-dependency tests. Figure 9: Temperature-dependent mechanical properties of the polymers: (**a**) tensile strength, (**b**) elastic modulus, (**c**) fracture strain, and (**d**) modulus of toughness. * The phase change from the ductile type to the brittleness type was observed by decreasing temperature. The fracture characteristics of PVDF and PE show the agglomerative and grainy forms and were considered to influence advanced tensile strength and elastic modulus. * However, for ABS, the shape was featured by a flat plane surface in the fracture surface and took place with little or no preceding plastic deformation, except at room temperature. This means that fracture characteristics such as the ductility and malleability could be predicted by evaluating the plane macroscopic observation. * At \(-50\)\({}^{\circ}\)C, the tensile properties of the polymers indicate that the increase in tensile strength and decrease in elongation by fracture were due to an increased strain rate. * At \(-100\)\({}^{\circ}\)C, failure characteristics were not appreciably different from strain rates of \(10^{-2}\) s\({}^{-1}\) and \(10^{-3}\) s\({}^{-1}\). It is considered that the mechanical property of the polymers at \(-100\)\({}^{\circ}\)C is influenced by low-temperature brittleness. * When compared with mechanical properties, it was indicated that PVDF has superior capability, and each polymer shows different fracture surface in terms of ductility and brittleness. Hence, this type of polymer can be considered for application at a suitable temperature range. * The tested polymers showed strain-rate- and temperature-dependent mechanical characteristics. The quantitative material properties tested at various temperatures and strain-rates can be used as material information for the finite element (FE) analysis and material parameters for the development of advanced constitutive models. Conceptualization, M.-S.K. and Y.K. ; methodology, Y.K. ; investigation, K.W.C. ; writing--original draft preparation, M.-S.K. and K.W.C. ; writing--review and editing, H.-J.J. and J.-H.K. All authors have read and agreed to the published version of the manuscript. This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry and Energy (MOTIE) of the Republic of Korea (2022400000090).