In this paper

a new method for evaluating the aging state of low-density polyethylene (LDPE) is studied through the space charge response analysis of LDPE samples in different aging states under a wide-band sinusoidal electric field

combined with physicochemical

electrical conductivity

and dielectric spectrum characteristics. The sinusoidal electric field frequency range is 0.5 mHz~10 kHz in the experiment

and the electric field amplitude is 10 kV/mm. The results show that: the average phase bulk charge density inside LDPE shows a Z-shaped trend with the electric field frequency varying within the range of 0.5 mHz~10 kHz. The accumulation amount of space charge at low frequencies is more than that at high frequencies. This phenomenon may be related to the larger charge injection amount due to the increased effective acting time of the electric field at low frequencies. With the decreased frequency of the high-frequency electric field

the fluctuation amplitude of the internal charge of the samples aged 0 h is small

and the internal charge of the samples aged 12 h and 24 h gradually increases. It is speculated that this phenomenon is related to the increase of ionic charge and implanted charge in the samples aged 12 h and 24 h. As aging progresses

the accumulation amount of LDPE internal charge increases under the same electric field frequency; the space charge density curve of the unaged sample turns at the electric field frequency of 10 Hz

while the turning threshold frequency (fc) of aged samples decreases. This phenomenon may be related to the easier charge injection because the destruction of large molecular structures of aged LDPE reduces the charge injection barrier. The charge injection threshold frequency fc of LDPE material under wide-band frequency electric field can be used as a parameter to evaluate its aging state.