## 3 Results and Discussion
### FTIR Analysis  
The FTIR spectra for the PP composites with glass fiber, ash and elastomer are shown in Figure 2. The first piece of information that Figure 2 provides is that the peaks for PP-25G-E and PP-25G-C-E have a lower intensity compared to PP-25G-C and PP-25G. This is to be expected as PP-25G-E and PP-25G-C-E have lower PP content, as shown in Table 1. The peaks indicated in Figure 2, ranging from 973 cm\({}^{-1}\) to 997 cm\({}^{-1}\), are all related to the -CH\({}_{3}\) asymmetric rocking vibration and C-C asymmetric stretching vibration of PP. Similarly, the peaks highlighted at 841 cm\({}^{-1}\) are linked to the -CH\({}_{2}\) rocking vibration of PP. The peak found at 997 cm\({}^{-1}\) is associated with the crystalline phase of PP (\(\alpha\) and \(\beta\)  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \(\alpha\)PP & \(\alpha\)PP & \(\alpha\)PP & \(\alpha\)PP & \(\alpha\)PP & \(\alpha\)PP & \(\alpha\)PP \\  & **(110)** & **(040)** & **(130)** & **(111)** & **(13-1)** & **(101)** & **IO** \\ \hline  & 20 & 14.096 & 16.942 & 18.597 & 21.212 & 21.889 & & \\ PP-25G & d (Å) & 6.277 & 5.229 & 4.767 & 4.185 & 4.057 & & \\ CI = 66\% & Height (cps) & 16,666 & 15,184 & 7433 & 6099 & 6201 & & 0.911 \\ Size (Å) & 120 & 152 & 111 & 78 & 119 & & \\  & FWHM (\({}^{\circ}\)) & 0.663 & 0.5273 & 0.7244 & 1.0299 & 0.6748 & & \\ \hline  & 20 & 14.096 & 16.927 & 18.591 & 21.127 & 21.819 & 26.55 & \\ PP-25G-C & d (Å) & 6.277 & 5.233 & 4.768 & 4.201 & 4.069 & 3.3539 & \\ CI = 70\% & Height (cps) & 16,998 & 23,259 & 8362 & 3268 & 7568 & 690.12 & 1.368 \\  & Size (Å) & 128 & 149 & 110 & 124 & 94 & 215.31 & \\  & FWHM (\({}^{\circ}\)) & 0.6252 & 0.5363 & 0.7297 & 0.6506 & 0.8597 & 0.4031 & \\ \hline  & 20 & 14.081 & 16.911 & 18.576 & 21.136 & 21.876 & & \\ PP-25G-E & d (Å) & 6.284 & 5.238 & 4.772 & 4.2 & 4.059 & & \\ CI = 63\% & Height (cps) & 16,645 & 16,044 & 8270 & 5958 & 6315 & & 0.964 \\  & Size (Å) & 122 & 148 & 107 & 74 & 110 & & \\  & FWHM (\({}^{\circ}\)) & 0.6546 & 0.5426 & 0.749 & 1.0852 & 0.732 & & \\ \hline  & 20 & 14.07 & 16.896 & 18.517 & 21.131 & 21.828 & 26.5355 & \\ PP-25G-C-E & d (Å) & 6.286 & 5.243 & 4.787 & 4.200 & 4.068 & 3.356 & \\ CI = 58\% & Height (cps) & 11,862 & 12,157 & 6002 & 4175 & 7052 & 669.3 & 1.025 \\  & Size (Å) & 121 & 146 & 109 & 115 & 94 & 225.69 & \\  & FWHM (\({}^{\circ}\)) & 0.6572 & 0.5466 & 0.733 & 0.7003 & 0.8559 & 0.3616 & \\ \hline \hline \end{tabular}
\end{table}
Table 2: XRD results for the studied PP composites.  
Figure 1: XRD patterns for PP composites in comparison with PP-25G.  
forms), while the 973 cm\({}^{-1}\) peak is connected to both the crystalline and amorphous phases of PP [34]. The degree of crystallinity calculated from the ratio of the maximum intensities of the two peaks [29] varies in the order PP-25-E > PP-25G-C-E > PP-25G-C > PP-25G. The peaks at 1166 cm\({}^{-1}\) can be associated with the rocking vibration of -CH\({}_{3}\) while the peaks ranging from 1375 cm\({}^{-1}\) to 1458 cm\({}^{-1}\) are related to the symmetrical bending vibration of -CH\({}_{3}\)[35; 36]. In the case of composites containing elastomer, PP-25G-E and PP-25G-C-E, a slight shift of these peaks to the left is observed, proof of the interaction between PP and the ethylene-propylene blocks in the elastomer. New FTIR bands at 1578 and 1541 cm\({}^{-1}\) were observed in Figure 2 for PP-25G-C and at 1570 and 1543 cm\({}^{-1}\) for PP-25G-C-E, being specific to the addition of the treated ash additive, more specifically from the dispersion agent used for the fly ash surface treatment [12], and can be associated with the -COO\({}^{-}\) antisymmetric stretching vibration group [37; 38; 39].