Development of Flexible Lead‐Free Natural Rubber‐Based Composites With High Gamma Ray Shielding Efficiency

Gamma rays pose a significant threat to the health of nuclear personnel. Traditional gamma‐ray protection materials, primarily composed of lead‐based polymers, exhibit poor flexibility and toxic properties, among other limitations. These materials restrict personnel movement and may lead to health issues with prolonged use due to their toxicity. In this study, we developed a flexible composite material with favorable mechanical properties, fatigue resistance, and excellent radiation protection capabilities by incorporating micron‐sized bismuth (Bi) into natural rubber through an open‐mill mixing process. We characterized the effects of Bi content on the microstructure, vulcanization behavior, mechanical properties, and radiation shielding performance of the composite. Scanning electron microscopy was employed to examine the microstructure, revealing that Bi was uniformly dispersed within the natural rubber matrix. By investigating the vulcanization behavior, we have achieved excellent mechanical properties. The tensile strength of a filler content of 85% can reach 7.61 MPa, and it maintains excellent puncture resistance after 1000 cycles of 100% elongation, with the deformation remaining at around 7%. This composite achieved a radiation shielding efficiency of 70.0%, corresponding to a lead equivalent of 0.290 mmPb under 118 keV x‐rays. Compared to other lead‐free rubber‐based radiation protection materials available in the market, its radiation protection performance is significantly enhanced.