Effect of Gamma-ray Irradiation on Trap Characteristics of Polyethylene Based Micro/Nanocomposites

As the main insulating material of nuclear power plant cables, polyethylene is exposed to high temperatures and irradiation and its service life is shortened. It is crucial to improve the insulating and electrical properties of irradiated polyethylene. In this study, low-density polyethylene (LDPE) based Boron Nitride $(\mathrm {B}\mathrm {N})/\mathrm {S}\mathrm {i}\mathrm {O}_{2}$ Micro/nanocomposites have been prepared to investigate the effect gamma-ray irradiation on the trap characteristics. The irradiation was carried out in air and the total dose was $0\mathrm {k}\mathrm {G}\mathrm {y}, 100\mathrm {k}\mathrm {G}\mathrm {y}, 500\mathrm {k}\mathrm {G}\mathrm {y}$ and $1000~\mathrm {k}\mathrm {G}\mathrm {y}$. The surface potential decay of gamma-irradiated composites filled with various contents of micro- and nano-sized particles was measured, and the trap distribution and the carrier mobility of composites could be obtained. It was found that the trap depth decreased as the total dose increased from $0 \mathrm {k}\mathrm {G}\mathrm {y}$ to $1000~\mathrm {k}\mathrm {G}\mathrm {y}.$ The trap depth of the composites containing 20 wt% micro-BN and 5 wt% nano-SiO2 did not change significantly with the growth of irradiation dose. It is considered that the addition of micro- and nano- particles plays a better role in hindering the chemical reactions such as crosslinking and oxidation.