Investigation of charge trapping and detrapping dynamics in LDPE, HDPE and XLPE

In this paper, charge trapping and detrapping dynamics of PE-based materials, i.e., LDPE, HDPE, XLPE were investigated by isothermal surface potential decay method (ISPD). The whole charge transport process including ions generation process in the air, charge trapping in the top surface, the surface potential establishing process, the charge migration process in the bulk was considered in these PE-based materials. The results showed that the trapping process was closely related to the capture cross section, the injected carrier concentration and the trap level. The established surface potential was mainly determined by the captured carriers in the top surface of the PE-based materials. In addition, it was found that the mobility of LDPE was much larger than that of XLPE and HDPE. And it is shown that deep traps may play a more important role in the charge migration process than shallow traps in these PE-based materials. It is indicated that the discrepancy of charge trapping and detrapping dynamics between these PE-based materials may be attributed to the different microscopic morphology.