## 3 Results  
### Characterization of the Structural and Morphological Properties of Tungsten-Reinforced Polyisoprene  
3.1.1. Material Characterization of Tungsten-Reinforced Polyisoprene: SEM and EDX for Microstructural and Elemental Analysis  
The SEM images (Figure 3) compare NR and WO\({}_{3}\)-reinforced polyisoprene at 500\(\times\), 1500\(\times\), and 3000\(\times\) magnifications. The NR picture at 500\(\times\) mostly shows a smooth surface but also some cracks and small granular structures. The 500\(\times\) scan of WO\({}_{3}\)-reinforced polyisoprene reveals a unique morphology, with clusters of elongated and plate-like structures. Showing the polyisoprene and WO\({}_{3}\) particles interact strongly within these structures, which makes the structures more stable. The 1500\(\times\) reveals greater detail of the NR showing surface-scattered granules, indicating phase separation or minor inhomogeneities in the matrix. The 1500\(\times\) scan of the WO\({}_{3}\)-reinforced polyisoprene shows more prominent well-aligned plate-like structures. Suggesting a higher degree of reinforcement, which could contribute to improvements in mechanical properties, such as stiffness and tensile strength. Figure 2: The experimental setup for evaluating the shielding efficacy of materials against Tc-99m radiation using an RSD anthropomorphic phantom. The phantom simulates human tissue and is equipped with radiation dosimeters Hp(3), Hp(10), and Hp(0.07), placed at the eye lens, thoracic, and abdominal regions, respectively, to measure dose equivalents. Two configurations were assessed: (**A**) without shielding material and (**B**) with shielding material placed between the Tc-99m radiation source and the phantom. In both configurations, the Tc-99m source was positioned 30 cm in front of the phantom. The higher 3000\(\times\) magnification of NR reveals fine particles and an increase in surface roughness, as well as highlighting small-scale heterogeneities within the polymer structure. The 3000\(\times\) magnification image of the WO\({}_{3}\)-reinforced polyisoprene shows the particles being well-dispersed, to form a highly ordered and interconnected structure. This highly ordered alignment of the needle-like WO\({}_{3}\)-reinforced polyisoprene nanostructures and organization suggest strong interfacial adhesion between the polymer and the WO\({}_{3}\) filler, enhancing its thermal stability and mechanical performance. To confirm the distribution of WO\({}_{3}\) within the polymer matrix, the EDX elemental analysis results are illustrated in Figure 4. The SEM image of NR displays a relatively uniform morphology with dispersed particles. The EDX analysis revealed a high carbon content (68.3 wt%), characteristic of organic rubber matrices. Oxygen (6.5 wt%), sodium (3.6 wt%), zinc (16.9 wt%), and sulfur (4.7 wt%) were also detected. The elemental mapping indicates a uniform homogeneous distribution of carbon, while zinc and sulfur appear as  
Figure 3: Scanning electron microscopy (SEM) images of polyisoprene (natural rubber, NR) and tungsten oxide (WO\({}_{3}\))-reinforced polyisoprene at different magnifications (500\(\times\), 1500\(\times\), and 3000\(\times\)). dispersed clusters, potentially linked to the vulcanization process. The SEM image of the WO\({}_{3}\)-reinforced sample exhibits a more heterogeneous and rougher appearance, probably due to the presence of WO\({}_{3}\) particles. The carbon level decreased significantly (14.4 wt%), suggesting partial replacement of the polymer matrix with inorganic filler. The presence of tungsten (52.0 wt%) indicates that WO\({}_{3}\) has been successfully incorporated into the material. Increased oxygen (21.4 wt%) and sodium (10.1 wt%) concentrations imply more interactions between the polymer and the oxide filler. Zinc (2.1 wt%) is present, albeit at a lower quantity than NR, which might be owing to the filler impacting additive dispersion. The EDX elemental analysis indicates that adding WO\({}_{3}\) considerably modifies the elemental composition of polyisoprene.