Fabrication and Radiation Shielding Properties of (<scp>HDPE</scp>/Colemanite)‐(<scp>HDPE</scp>/<scp>Bi₂O₃</scp>) Multi‐Layer Composites

ABSTRACT In this study, 5, 10, and 15 wt% colemanite (Ca 2 B 6 O 11 ‐5H 2 O) and 15 wt% Bi 2 O 3 filled high‐density polyethylene (HDPE) composites were fabricated by conventional melt extrusion processing techniques in the form of a layered structure to absorb both neutron radiation and secondary radiation resulting from neutron‐induced reactions. In the layered structure, HDPE was used to slow down neutrons, while colemanite and Bi 2 O 3 were used to trap thermal neutrons and secondary gamma radiation respectively. The properties of the colemanite/HDPE and Bi 2 O 3 /HDPE composites were investigated by scanning electron microscopy (SEM), x‐ray diffraction (XRD), and thermogravimetric analysis (TGA). The mechanical properties (tensile and hardness) of the composites were also investigated. The results showed that the addition of colemanite and Bi 2 O 3 particles did not significantly alter the thermal and mechanical properties of the HDPE composites. The total macroscopic cross‐section of the composites was determined using a 239 Pu‐Be (α,n) neutron source, while their linear and mass attenuation coefficients were determined using a 137 Cs gamma‐ray source. The material with the best neutron absorption rate is 15 wt% colemanite‐filled HDPE (2.31 ± 003 cm −1 ), while the best gamma‐absorbing material is 15 wt% Bi 2 O 3 filled HDPE (0.114 cm −1 ). The 15 wt% colemanite, 15 wt% Bi 2 O 3 doped HDPE layered structure has 1.72 ± 0.05 cm −1 macroscopic cross‐sections and 0.098 linear attenuation coefficient. The results show that filled colemanite HDPE composites improve neutron shielding properties and Bi 2 O 3 filled HDPE composites provide good shielding performance for gamma rays.