A comprehensive study on the irradiation damage of PP/PbO composites under γ-ray exposure

Polymer-based composites show great potential as lightweight radiation shielding materials; however, a significant gap remains in understanding their performance stability under extreme high-energy radiation conditions. For this reason, the present study pioneers a systematic investigation into the dynamic evolution of polypropylene/lead oxide (PP/PbO) composite with heterogeneous network structure exposed to high-energy γ ray. Through multiscale characterisation spanning structure, surface, rheological behaviour, crystallinity, thermal stability, mechanical property, and shielding efficiency across incremental radiation doses, we reveal the fundamental role of heterogeneous network structure in irradiation damage mechanisms. The results indicate that although γ-ray irradiation indeed leads to varying degrees of degradation in various aspects of PP/PbO composite, the formation of a heterogeneous network structure mitigates the irradiation damage to a large extent, enabling the composite to exhibit superior tensile and impact strength compared to previously reported PP-based materials. More importantly, PP/PbO composite with a heterogeneous network structure retains a shielding efficiency of approximately 7.67% after high-energy ray exposure (120 kGy), which is 1.5 times higher than that of its unmodified counterpart (conventional polypropylne/lead oxide, CPP/PbO) at the same irradiation dose. Meanwhile, the half-value layer and tenth-value layer values of PP/PbO composite increased by less than 13.7% compared to the unirradiated state and are only 60% of those of CPP/PbO. The tensile strength of PP/PbO composite (120 kGy) decreases by only 11% after irradiation but still remains above 20 MPa. This work establishes comprehensive structure–property relationships that could facilitate the development of radiation-resistant polymer-based composites for extreme service conditions.