## 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
Figure 9C presents HVL values as a function of photon energy in the range of 10\({}^{-4}\) MeV to 10\({}^{6}\) MeV. The NR shows significantly higher HVL values. PbO\({}_{2}\) and WO\({}_{3}\)-reinforced composites show significantly lower HVL values than NR, highlighting their superior shielding performance. Increasing WO\({}_{3}\) content results in a systematic reduction in HVL. The PbO\({}_{2}\) and WO\({}_{3}\)-rich composites (\(\geq\)75%) exhibit the lowest HVL, making them good candidates for Tc-99m radiation shielding. The graph (Figure 9D) illustrates the variation of tenth-value layer (TVL) as a function of photon energy in the range of 10\({}^{-4}\) MeV to 10\({}^{6}\) MeV. Indicating that at lower photon energies (below 10 keV), the TVL values rise noticeably. Thereafter, they show a more constant trend in the middle energy range (10 keV to 10 MeV). For high-energy photons (>10\({}^{3}\) MeV), a rapid increase in TVL indicates a decrease in shielding efficacy resulting from the predominance of Compton scattering and pair creation. The inset graph illustrates the TVL values at the characteristic energy of 140 keV for Tc-99m. PbO\({}_{2}\) and high-percentage WO\({}_{3}\) composites (90% and 100%) exhibit the lowest TVL values, thereby confirming their effectiveness for Tc-99m shielding. The mean distance a photon travels within a material before absorption or scattering is called the mean free path (MFP). Due to more photon interactions with the material, a lower MFP improves shielding. The MFP graph (Figure 10A) shows that in the low-energy region (10\({}^{-4}\) to 10\({}^{-2}\) MeV), all materials have very short mean free path values, indicating intense photon interactions attributable to the predominance of the photoelectric effect. In the intermediate-energy range (10\({}^{-2}\) to 10 MeV), the MFP rises as the interaction mechanism shifts from photoelectric absorption to Compton scattering. In the high-energy range (>10 MeV), a plateau occurs as MFP values increase, as pair creation emerges as the predominant interaction mechanism. Figure 10B shows the Neff as a function of photon energy, emphasizing its energy-dependent variability. Neff shows considerable variances for all materials along the photon energy spectrum, particularly in the low-energy band (<10\({}^{-2}\) MeV). NR has the lowest effective electron density among all energies, suggesting limited radiation interaction capabilities. At higher photon energies (>100 MeV), the effective electron density stabilizes, indicating there is less of a reliance on the composition of the material. For Tc-99m shielding the inset graph indicates that PbO\({}_{2}\) and high-WO\({}_{3}\) composites (90% and 100%) display the highest effective electron densities, making them optimal choices for the Tc-99m shielding. Effective conductivity is a crucial parameter in radiation shielding, reflecting the material's ability to conduct charge under radiation exposure. Figure 10C presents the results of the Ceff analysis, illustrating the relationship between Ceff and photon energy, covering a wide range of values from 10\({}^{-4}\) MeV to 10\({}^{6}\) MeV. The overall pattern noted in all materials indicates a preliminary rise in Ceff at lower photon energies, reaching a peak around 0.01 to 0.1 MeV. After that, there is a decrease followed by a stabilization at elevated energies. PbO\({}_{2}\) has the greatest Ceff values at all photon energies, implying good charge transfer and making it a good shielding material. NR has the lowest Ceff, suggesting limited charge transport capability and poor radiation shielding. Furthermore, by increasing addition of WO\({}_{3}\) concentration to WO\({}_{3}\)-reinforced NR it was shown to improve shielding performance. The atomic cross section (ACS) values for each material as a function of photon energy are shown in Figure 10D. The findings show how effectively WO\({}_{3}\)-enhanced polyisoprene composites shield Tc-99m radiation. PbO\({}_{2}\) and 100% WO\({}_{3}\) achieve the most effective shielding performance.