Fabrication, characterization and optimization design of flexible materials for X-ray shielding with high efficiency

In this paper, a kind of thermoplastic elastomer Polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS) is used for the fabrication of W, Pb, Bi, Gd₂O₃, BaSO₄ and Sn particles dispersed flexible composites for X-ray shielding. Through melting and blending technology, functional elements are well dispersed in the SEBS matrix even without any chemical interactions between the chemical groups of SEBS and the fillers. Based on mass attenuation coefficient rules of mixture or compound in XCOM program, X-ray shielding efficiency of the samples are predicted by mass attenuation coefficient (μ_m), linear attenuation coefficient (μ), half value layer (HVL) and equivalent atomic number (Z_eff). It is predicted by XCOM program that three shielding levels are actually found, in which W, Pb and Bi doped samples have the strongest X-ray shielding ability, with Gd₂O₃, BaSO₄ and Sn providing lesser effectiveness. Then, predictions of XCOM and MCNP codes are verified by the experimental measurement of shielding efficiency at X-ray tube voltages of 80 kV_p and 120 kV_p. Due to the different K-layer photon absorption edges of elements W and Bi, sample doped with proportion of W:Bi = 5:5 is able to achieve a complementation in the weak absorption region of 70 keV–90 keV. What is more, a layer of Gd₂O₃ doped sample stacked on W:Bi = 5:5 is able to greatly improve the shielding efficiency in the region of 50 keV–90 keV, indicating a more effective shielding design achieved. To sum up, based on the thermoplastic elastomer SEBS, a series of X-ray shielding functional materials with high flexibility and performance are prepared, and both theoretical and experimental results show that they could be of great potential values in the field of X-ray shielding.