## 4 Results and Discussion
Since the permeability data for ethane in PMPentyne and data for butane in PMPentene were missing, the values used for further calculations and shown in the figures were obtained by correlation approach described in Section 3.3. \begin{table}
\begin{tabular}{c c c c} \hline \hline _P,_ **Barrer** & **CH4** & **C2H6** & **C3H8** \\ \hline \multicolumn{4}{c}{**t = 80 \({}^{\circ}\)C**} \\ \(P_{a}\) & 146 & 135 & 123 \\ \(P_{c}\) & 31 & 11.8 & 4.4 \\ \multicolumn{4}{c}{**t = 25 \({}^{\circ}\)C**} \\ \(P_{a}\) & 11 & 11.8 & - \\ \(P_{c}\) & 11 & 11.8 & - \\ \multicolumn{4}{c}{**t = 10 \({}^{\circ}\)C**} \\ \(P_{a}\) & 9.0 & 7.8 & - \\ \(P_{c}\) & 9.0 & 7.4 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 4: The gas permeability coefficients in the amorphous (\(P_{a}\)) and crystalline (\(P_{c}\)) phases of PMPentene at different temperatures. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **CH4** & **C4H10** \\ \hline \(S\), cm\({}^{3}\)/(cm\({}^{3}\cdot\)cmHg) & 0.025 & 1.49 \\ \(P\), Barrer & 1500 & 9100 \\ \(D\), cm\({}^{2}\)/s & \(6.0\times 10^{-6}\) & \(6.1\times 10^{-7}\) \\ \(\Delta H_{S}\), kJ/mol & \(-17.3\) & \(-38.5\) \\ \(E_{P}\), kJ/mol & \(-8.3\) & \(-25.9\) \\ \(E_{D}\), kJ/mol & 9.0 & 12.6 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Membrane parameters for methane and butane in PMPentyne at 25 \({}^{\circ}\)C [31; 32; 33]. Figure 4: Permeability coefficients of PMPentyne and PMPentene at 10 \({}^{\circ}\)C: \(\blacksquare\), \(\bullet\) experimental data; \(\Box\), \(\bigcirc\) data calculated using correlation approach (Equations (7)–(9)). Figure 5: Diffusion coefficients of PMPentyne and PMPentene at 10 \({}^{\circ}\)C: \(\blacksquare\) data calculated from \(D=P/S\), \(\bullet\) experimental data; \(\bigcirc\) calculated using correlation approach (Equations (7)–(9)). Figure 6: Permeability coefficients of PMPentyne and PMPentene at 25 \({}^{\circ}\)C. \(\blacksquare\), \(\bullet\) experimental data; \(\Box\), \(\bigcirc\) data calculated using correlation approach (Equations (7)–(9)). Figure 8: Permeability coefficients of PMPentyne and PMPentene (with amorphous-crystalline dispersion) at 80 \({}^{\circ}\)C. \(\bullet\) experimental data; \(\blacktriangle\), \(\blacktriangledown\) data calculated using two-phase model (Equations (2) and (3)); \(\blacksquare\) extrapolated from experimental data; \(\square\), \(\square\) data calculated using correlation approach (Equations (7)–(9)). Figure 7: Diffusion coefficients of PMPentyne and PMPentene at 25 \({}^{\circ}\)C: \(\blacksquare\) data calculated from \(D=P/S\), \(\bullet\) experimental data; \(\square\) calculated using correlation approach (Equations (7)–(9)). Figure 9: Diffusion coefficients of PMPentyne and PMPentene (with amorphous-crystalline dispersion) at 80 \({}^{\circ}\)C. \(\bullet\) experimental data; \(\blacktriangle\), \(\blacktriangledown\) data calculated using two-phase model (Equations (2) and (3)); \(\blacksquare\) data calculated from \(D=P/S\); \(\square\) calculated using correlation approach (Equations (7)–(9)). Thus, the combination of experimental and theoretical approaches allowed observation of the change in the permeability properties of these polymers in the temperature range 10-80 \({}^{\circ}\)C, which includes the T\({}_{\text{g}}\) of PMPentene. It can be seen from Figures 8 and 9 and Tables 3 and 4 that the selectivity of the diffusion and permeability of PMPentene crystalline phase exceeds these parameters for the amorphous phase at 80 \({}^{\circ}\)C, which must be taken into account when using PMPentene membranes at temperatures above T\({}_{\text{g}}\). It can be seen from Figures 4-9 that despite the similar physical densities of the studied polymers and their chemical structures there is a significant difference in permeability levels (2-3 orders of magnitude) and opposite trends in separation selectivity. It is worth noting that PMPentene is a methane-selective polymer and PMPentyne is a butane-selective polymer throughout the studied temperature range (Tables 6 and 7).