Radiation Attenuation Performance of Highly Filled Tungsten/TPU Composites via Anchor–Chain Dispersant-Based Interfacial Design

Environmentally friendly radiation shielding materials for medical institutions require lightweight characteristics and high flexibility as key performance indicators. One promising approach is the incorporation of lead-free materials that combine high-density shielding fillers with polymer matrices. High filler loading is necessary to maintain shielding performance while preserving the inherent flexibility of the polymer. However, during the mixing of shielding materials with polymers, microvoids may form. Therefore, strategies are required to enhance structural densification of the composite by reducing microvoid formation. This study aims to investigate the effects of interfacial design using an anchor–chain dispersant (APTES: 3-aminopropyltriethoxysilane) on micropore formation, effective density, and X-ray shielding performance in highly filled tungsten/thermoplastic polyurethane (TPU) composites. TPU-based composite shielding sheets containing 75–90 wt% tungsten were fabricated. The dispersant (APTES) can adsorb onto the surface of metal particles and form a stabilization layer. In this study, the observed reduction in particle agglomeration and porosity upon addition of the dispersant suggests that interfacial stabilization was induced. As a result, in the 85 wt% composite sheet, the porosity decreased from 5.89% without the dispersant to 0.56% with the dispersant, leading to an improvement in the densification level and effective density of the sheet. Under the same thickness condition (0.25 mm), the dispersant-containing sheet exhibited a shielding efficiency that was 3–4% p higher than that of the sheet without dispersant in the 100–120 kVp range. Meanwhile, as the tungsten content increased, the overall density and shielding efficiency of the sheets also increased. At 90 wt% tungsten loading, the composite demonstrated shielding performance approaching that of conventional lead shielding even at a reduced thickness. These results indicate that interfacial design using an anchor–chain dispersant is an effective processing strategy for improving density uniformity and radiation shielding performance in highly filled tungsten/TPU composite shielding materials by controlling microvoid formation.