Enhancing Mechanical and γ‐Ray Shielding Properties of Lightweight PP / Bi 2 O 3 Composites Through the Toughening and Compatibilization

ABSTRACT Polymer matrix composites have attracted wide interest for radiation protection due to their processability, flexibility, and capacity to host high‐Z fillers. However, inadequate filler dispersion reduces overall performance and hinders weight reduction. In this study, polypropylene/bismuth oxide composites are prepared by melt blending. Polybutadiene latex (PBL) is used as a toughening agent, and acrylamide (AM) serves as a compatibilizer to prepare the BPPA composite. The PBL/AM system strengthens phase‐interface bonding, improves Bi 2 O 3 dispersion, and increases the degree of branching, as the long‐chain branching index rises by 2.44 times. As a result, the composites show enhanced mechanical properties, thermal stability, and γ‐ray attenuation. The impact strength rises by 45.00%, the initial weight‐loss temperature increases by 77.30°C, and the radiation protection efficiency rises by 10.44% at 59.6 keV. Lightweight porous samples are further prepared through supercritical CO 2 foaming. The extended photon transmission path in the cellular structure reduces density to 18.18% of the unfoamed composite while maintaining a shielding efficiency of 35.42% at 59.6 keV. These results confirm the lightweight and high‐shielding capabilities of the developed material and offer guidance for the joint use of PBL and AM to improve composite performance and design advanced lead‐free polymer shields.