## 3 Results and Discussion  
### X-ray Diffraction Analysis  
XRD patterns for \(\alpha\)PP in composites are shown in Figure 1, identified according to a study by [PERSON] et al. [26]. The \(\alpha\) phase was recognized in PP-25G at 20 = 14.09\({}^{\circ}\), 16.94\({}^{\circ}\), 18.59\({}^{\circ}\), 21.21\({}^{\circ}\) and 21.88\({}^{\circ}\), which are associated with the (110), (040), (130), (111) and (13-1) crystallographic planes. A study by [PERSON] et al. [27] showed similar diffraction peaks and crystalline planes for the \(\alpha\)-form crystal of PP and indicated that PP-glass fiber composites processed by injection molding have proper orientation of polymeric chains. [PERSON] et al. [28] and [PERSON] and [PERSON] [29] demonstrated that the injected PP samples exhibit a skin-core morphological structure that depends on both the intrinsic properties of the PP and the processing conditions. They found the existence of three crystalline layers on the thickness of the injected sample (a layer strongly oriented in the direction of the melt flow (non-spherulitic skin)), with thicknesses up to about 400 nm on the surface, a microspherulitic intermediate layer with a large number of nucleated spherulites at some depth, and a layer (core) composed of spherulites with large dimensions and low orientation in the middle. In the case of our composites, we expected that the morphological structure of PP would be influenced by the different effect of each component on the nucleation, crystallization rate, orientation and size of the spherulites of the \(\alpha\)PP. With the addition of treated ash powder, the presence of another peak can be seen in PP-25G-C and PP-25G-C-E composites at 20 = 26.55\({}^{\circ}\) and 26.53\({}^{\circ}\), respectively, which correlate with the (101) SiO\({}_{2}\) crystallographic plane (PDF card No. 01-090-3640). It is also observed that by incorporating the ash, the height of the (040) diffraction peak increases a lot compared to the (110) diffraction peak, which remains almost unchanged. This behavior demonstrates that the ash affects the orientation of the \(\alpha\)PP crystallites. A similar effect was reported by [PERSON] et al. [30] when incorporating talc in iPP. They found that talc crystals disrupt the spherulitic morphology of PP and orient in a plane parallel to the surface. The CI and the OI of \(\alpha\)PP, calculated from X-ray diffraction, showed highest values for the composite PP-25G-C, evidence of the interaction between PP, MA, G and C and low chain mobility. In this case, the adhesion at the polymer matrix-filler interface is stronger due to the additional interactions between the dispersion agent and each of the composite components. Thus, the surface-treated fly-ash, C, can interact with PP through propylene groups and with PP-MA through -OH and ester groups from poly(propylene glycol adipate). After the addition of elastomer, both the crystallinity index and orientation index showed diminished evidence of the interaction between PP and E. This could be explained by the recrystallization of a part of the \(\alpha\)PP crystals with the change in orientation direction. The high nucleation capacity of SEBS at the interface with iPP and the opposite effect it has on the orientation of crystallites with respect to minerals are known [30]. The addition of SEBS can result in a complex morphology consisting of both transcrystalline layers on the surface and radial spherulites inside the sample. It should be noted, however, that the OI is higher in the case of composites that, in addition to glass fiber, also contain other additives compared to composites with only 25% glass fiber. From Table 2, we see that the peaks that are characteristic for the \(\alpha\) crystalline phase of PP present dissimilar intensities for PP-25G-C (the highest values for the height of the (110) and (040) diffraction peaks, so increased concentration of \(\alpha\)PP) and PP-25G-C-E (the lowest values for the height of the (110) and (040) diffraction peaks) compared to PP-25G.