## 3 Results
### Characterization of the Structural and Morphological Properties of Tungsten-Reinforced Polyisoprene
#### 3.1.2 Structural Properties of Tungsten-Reinforced Polyisoprene Characterized by X-Ray Diffraction  
The results of the XRD analysis (Figure 5) emphasize the structural differences between NR and tungsten-reinforced polyisoprene. Figure 5A depicts the XRD pattern of NR, which reveals the crystalline phases contained in the sample. The diffraction peaks correspond to the main crystallographic components. ZnO (matching well with the standard of Joint Committee on Powder Diffraction Standards (JCPDS) number 01-079-5604) is a regularly used activator in the vulcanization process [43]. Sulfur (S) (matching well with the standard JCPDS number 00-064-0585) is a vulcanizing agent that promotes crosslinking in the polymer matrix [44; 45; 46]. Zinc dimethyldiocarbamate (matching well with the standard JCPDS number 00-005-0315) acts as an accelerator during the vulcanization process [44; 47; 48]. Thiram (C\({}_{6}\)H\({}_{12}\)N\({}_{2}\)S\({}_{4}\)) (matching well with the standard JCPDS number 00-041-1876) is a vulcanizing accelerator. The patterns corroborate the nature of the NR formulation, which includes vulcanizing chemicals and fillers [49]. Figure 5: X-ray diffraction (XRD) analysis of polyisoprene (natural rubber, NR) and tungsten oxide (WO\({}_{3}\))-reinforced polyisoprene. (**A**) XRD pattern of NR, with corresponding phase identification for major crystalline components, including zinc oxide (ZnO), sulfur (S), zinc dimethylditiocarbamate, and thiram. (**B**) XRD pattern of WO\({}_{3}\)-reinforced polyisoprene, showing characteristic peaks of sodium tungsten oxide hydrate (Na\({}_{2}\)WO\({}_{4}\) 2H\({}_{2}\)O), tungsten oxide (WO\({}_{3}\)), and ZnO. (**C**) Comparative XRD patterns of NR and WO\({}_{3}\)-reinforced polyisoprene, highlighting differences in crystallinity and phase composition. (**D**) Stacked XRD patterns of NR and WO\({}_{3}\)-reinforced polyisoprene for direct visualization of peak variations. Figure 5B shows the XRD pattern for polyisoprene reinforced with WO\({}_{3}\). The diffraction peaks reveal the existence of crystallographic phases. Sodium tungsten oxide hydrate (Na\({}_{2}\)WO\({}_{4}\)\(\cdot\)2H\({}_{2}\)O) (matching well with the standard JCPDS number 00-047-0064) may result from interactions between tungsten compounds and moisture during processing [50]. ZnO is a crucial component in the composite. WO\({}_{3}\) (matching well with the standard JCPDS number 01-071-0305) was found in the main reinforcement phase, indicating its effective integration into the polymer matrix [51]. The inclusion of WO\({}_{3}\) into the polyisoprene matrix creates extra diffraction peaks attributable to tungsten-based compounds. This indicates a significant shift in the crystalline structure of the composite, which will most likely affect its mechanical and physicochemical characteristics. Figure 5C presents a comparative XRD analysis of NR (red) and WO\({}_{3}\)-reinforced polyisoprene (blue), highlighting key differences in their diffraction patterns. Both NR and WO\({}_{3}\)-reinforced polyisoprene exhibit characteristic diffraction peaks across the 2\(\theta\) range, indicating the presence of crystalline phases in both materials. However, the peak intensities vary significantly between the two samples. Crystalline phase identification reveals that NR (red) primarily contains peaks associated with ZnO, sulfur (S), and vulcanization accelerators such as zinc dimethyldithiocarbamate and thiram. In contrast, WO\({}_{3}\)-reinforced polyisoprene exhibits additional diffraction peaks corresponding to WO\({}_{3}\) and Na\({}_{2}\)WO\({}_{4}\)\(\cdot\)2H\({}_{2}\)O, confirming successful incorporation of the reinforcing agent. The addition of WO\({}_{3}\) increases the number of diffraction peaks, suggesting improved crystallinity. WO\({}_{3}\)-reinforced polyisoprene exhibited sharper and more intense peaks, indicating enhanced structural ordering within the composite.