Flexible stretchable low-energy X-ray (30–80 keV) radiation shielding material: Low-melting-point Ga1In1Sn7Bi1 alloy/thermoplastic polyurethane composite

A highly flexible stretchable thermoplastic polyurethane (TPU) composite loaded with a low-melting-point Ga1In1Sn7Bi1 multiprincipal element alloy (LMPEA) was prepared, and its radiation shielding performance was evaluated. The fluid characteristic of LMPEA and the flexibility of TPU enable good interface compatibility. Ga1In1Sn7Bi1 LMPEA consists of two eutectic structures, and the liquid gallium-rich phases are distributed at the boundary of the InBi intermetallic compound and Sn solid solution. In the low-photon energy range of 30–80 keV, LMPEA has a theoretical specific lead equivalent of 0.803 mmPb/mm and a theoretical weight reduction of 17.27% compared with lead. To evaluate the photon attenuation capability for the LMPEA/TPU composites, the Phy-X procedure and Monte Carlo simulations were used to determine the shielding parameters, such as the mass attenuation coefficient, linear attenuation coefficient, half-value layer, tenth-value layer, mean free path, effective atomic number, and fast neutron removal cross section. The attenuation performance test of X-ray protective materials measured the actual lead equivalent. At the same thickness, the LMPEA/TPU composite (66.667, 50.000 wt% LMPEA loading) has a higher measured lead equivalent than the in-service medical shielding materials, which meets the lead equivalent requirements of X-ray protective clothing. LMPEA/TPU composites are nontoxic, lightweight, and have excellent low-energy X-ray shielding ability, offering great potential for application in medical wearable materials.