Comparative study of gamma-ray shielding performance of TiO2-reinforced PMMA and epoxy composites using Geant4 Monte Carlo simulations

Polymer-based composites containing high-atomic-number fillers have attracted considerable interest as potential lead-free radiation shielding materials. However, direct comparisons of different polymer matrices under identical computational conditions remain limited, making it difficult to isolate the influence of the polymer matrix on shielding performance. In this study, the gamma-ray shielding characteristics of TiO 2 -reinforced poly(methyl methacrylate) (PMMA) and epoxy composites containing 0–50 wt% TiO 2 were systematically evaluated using the Geant4 Monte Carlo simulation toolkit over a photon energy range of 0.0595–1.333 MeV. Composite densities were determined using the rule of mixtures, and key shielding parameters, including the mass attenuation coefficient (MAC), linear attenuation coefficient (LAC), half-value layer (HVL), mean free path (MFP), effective atomic number (Zeff), and radiation protection efficiency (RPE), were calculated. The simulation methodology was verified through comparison with the XCOM database, showing excellent agreement with relative deviations below 2%. The results demonstrate that increasing TiO 2 concentration enhances the shielding performance of both polymer systems by increasing the attenuation coefficients and Zeff while reducing the HVL and MFP. Among the investigated compositions, the epoxy/TiO 2 composites consistently exhibited superior shielding performance compared with the corresponding PMMA/TiO 2 composites, primarily due to their higher density. The improvement was most pronounced at low photon energies, whereas higher photon energies required greater material thicknesses to achieve comparable attenuation, as reflected by increased HVL values. The findings provide a systematic computational assessment of the influence of the polymer matrix on gamma-ray shielding performance under identical simulation conditions and offer theoretical guidance for the design of polymer-based radiation shielding materials. Nevertheless, the present work is limited to computational evaluation, and further experimental studies, including mechanical, thermal, durability, processing, and biocompatibility assessments, are required before practical implementation of these composites can be established.