## 3 Results and Discussion
### Crystalline Conformation  
In order to evaluate the crystalline type, XRD was used for characterization, and the profiles are displayed in Figure 4. The dominant crystalline structure in RPP was polypropylene, similar to VPP. The peak at 14.0\({}^{\circ}\), 16.8\({}^{\circ}\), 18.5\({}^{\circ}\), 25.4\({}^{\circ}\), and 28.6\({}^{\circ}\) of 2-theta, which was indicated at (110), (040), (130), (060), and (220) of the monoclinic crystal of i-PP in \(\alpha\)-form, appeared in all samples [12,13]. In addition, the trigonal crystals of i-PP in \(\beta\)-form were also detected at 16.0\({}^{\circ}\)[12,14]. The peaks at 21.5\({}^{\circ}\) and 23.8\({}^{\circ}\), which were indicated at (110) and (200) of the PE crystalline plane [15], were detected in the RPP samples. Furthermore, the diffraction peak at 27.5\({}^{\circ}\) appeared for the RPP samples, which was indicative of talc particles [16] in the matrix of PP. It can be seen from the peaks in Figure 4 that the crystalline type of RPP-extrusion was similar to the RPP-original, even though the tensile properties were significantly improved. The characterization by infrared microscope can define the chemical composition and the orientation of the crystalline and noncrystalline phases [17]. Figure 5a shows the IR spectra of VPP, RPP-original, and RPP-extrusion. The composition of the PP matrix [18,19] was detected as being dominant for all samples; however, the characteristic peak of PE was detected in RPP samples at 721 cm\({}^{-1}\), which was attributed to the rocking vibration [20]. In addition, there were no significant changes between the IR spectra of RPP-extrusion and RPP-original, even though the tensile properties were different. \begin{table}
\begin{tabular}{c c c c} \hline
**Tensile Properties** & **VPP** & **RPP-Original** & **RPP-Extrusion** \\ \hline Elongation at break (\%) & 405.00 \(\pm\) 25.10 \({}^{1}\) & 282.46 \(\pm\) 32.34 & 501.37 \(\pm\) 29.54 \\ Toughness (MJ/m\({}^{3}\)) & 89.94 \(\pm\) 5.51 & 57.92 \(\pm\) 7.03 & 101.16 \(\pm\) 5.97 \\ Yield stress (MPa) & 31.53 \(\pm\) 0.27 & 27.64 \(\pm\) 0.16 & 27.88 \(\pm\) 0.05 \\ Tensile fracture stress (MPa) & 21.67 \(\pm\) 0.04 & 19.30 \(\pm\) 0.28 & 19.77 \(\pm\) 0.18 \\ Young’s modulus (MPa) & 443.57 \(\pm\) 4.64 & 387.34 \(\pm\) 3.90 & 396.95 \(\pm\) 2.82 \\ \hline \end{tabular} \({}^{1}\) The average values followed by the standard deviation.  
\end{table} 
Table 2: Tensile properties of VPP, RPP-original, and RPP-extrusion. Figure 3: (**a**) Representative stress–strain curve of VPP, RPP-original, and RPP-extrusion; (**b**) Photo image of the elongated specimen after testing by tensile test. It was attractive to focus on the conformation of PP in the helix band at 998 cm\({}^{-1}\), which was a general conformation of PP polymorphs, and of the parallel band at 973 cm\({}^{-1}\), which was defined by the shorter helix segments [21]. Figure 5b shows the IR mapping of the absorbance peak area ratio between 998 cm\({}^{-1}\)/973 cm\({}^{-1}\) of the helix band/parallel band. VPP showed a high ratio range around 0.71-0.88, which can be attributed to the high amount of helix band, which related to the good mechanical properties. Conversely, a low ratio was detected in RPP-original. This could be attributed to the high amount of parallel band in RPP-original, which affected the poor tensile properties in RPP. Interestingly, a slight increase of ratio occurred in RPP-extrusion at 0.56-0.71. The helix bands of the PP conformation of RPP-extrusion were higher than for RPP-original, which could be attributed to the high amount of helix band. Figure 4: XRD profile of VPP, RPP-original, and RPP-extrusion. Figure 5: (a) IR spectra of VPP, RPP-original, and RPP-extrusion; (b) IR mapping for the ratio between the helix and parallel band. related to the improvement of tensile properties, similar to VPP. [PERSON] et al.