Multilayer Structuring of Nonleaded Metal (BiSn)/Polymer/Tungsten Composites for Enhanced gamma-Ray Shielding

To effectively attenuate unrecognized and/or unwanted exposures to high-energy gamma-rays which leads to occupational hazards when accumulated in a wide range of industries, nonleaded metal (bismuth(Bi)-tin(Sn))/polymer and tungsten (W) composites are prepared and tested. A eutectic alloy, BiSn, with a low melting temperature of 139 degrees C, is applied for the first time to prepare a gamma-ray shielding material. Compounding of the BiSn alloy/polymer is conducted in a twin screw mixer/extruder by exploiting the alloy's low melting temperature. Multilayer BiSn/polymer composites are prepared by pressing the extruded composites. The gamma-ray shielding efficiency of the composite is elucidated on the basis of the K-edge theory. To make a thinner but more efficient composite, W flakes are laminated onto the BiSn/polymer composite sheet. The produced (BiSn/polymer)/W composite sheet exhibits strong attenuation of gamma-rays, which is found to follow the Beer-Lambert law. A multilayer (BiSn/polymer)/W laminate can offer both a sufficient thickness with flexibility and an effective shielding against gamma-rays to meet the requirements for protective clothing or protective equipment. This work demonstrates that (BiSn/polymer)/W laminates can be used as a reliable Pb-substitution material to protect the human body from the high-energy gamma-rays.