PVA/PEG-based B₄C/Bi₂O₃ nanocomposite films: Physicochemical characterization and computational gamma- and...

PVA/PEG (80:20) blend films containing B₄C, Bi₂O₃, and hybrid B₄C/Bi₂O₃ fillers were prepared by solution casting and characterized to establish relationships among their structural, thermal, optical, electrical, morphological, and radiation-interaction properties. XRD analysis showed that filler incorporation reduced the crystallinity of the PVA/PEG matrix from 82.38% to 72.15%, 69.73%, and 57.26% for the Bi₂O₃-, B₄C-, and hybrid-filled films, respectively. The 20 wt% B₄C formulation exhibited the highest thermal stability T_50% = 380 °C and the most spatially uniform electrical response, whereas the hybrid composition exhibited the lowest optical band gap (3.32 eV) and greatest structural disorder. Gamma-ray attenuation was evaluated computationally using GAMOS 7.0 and Phy-X/PSD over 0.0595-1.50 MeV. The Bi₂O₃-containing composition exhibited the strongest calculated low-energy photon attenuation; at 0.0595 MeV, GAMOS yielded an LAC of 1.613 cm^-1, corresponding to an HVL of 0.430 cm. GAMOS and Phy-X results differed by approximately 0.7-5.1% at representative energies, providing a computational cross-check. Thermal-neutron calculations using the NIST/NCNR approach showed that the B₄C-containing composition had the highest macroscopic absorption cross section (9.158 cm^-1), the lowest transmission (42.28% at 0.060 cm), and the smallest 1/e penetration depth (0.070 cm), whereas differences in the calculated fast-neutron removal cross section were modest. These results indicate complementary roles of Bi₂O₃ in low-energy photon attenuation and B₄C in thermal-neutron absorption. The shielding results are computational and require experimental validation before practical implementation.