In order to study the influences of non-isothermal crystallization on space charge characteristics in low-density polyethylene（LDPE） at temperature fields

three types of LDPE samples with different annealing rates were prepared

denoted as LDPE-I（ice water）

LDPE-A（air）

and LDPE-S（slow）. Space charge property was tested at temperature fields（20 ℃

40 ℃

and 60 ℃） based on the pulsed electro-acoustic（PEA） method. The results show that a lower annealing rate benefits to the crystallization of LDPE

resulting in higher crystallinity

larger size of crystal cell

and more uniform size distribution. Positive packet-like space charge can be observed in all samples under-100 MV/m at 20 ℃

and LDPE-I samples have the largest injection rate and mobility. Positive-like space charge only appears in LDPE-I samples at 40 ℃and 60 ℃. These phenomena are discussed from the aspects of apparent carrier mobility and trap depth during depolarization process at 20 ℃. LDPE-I samples possess smaller size of crystal cell

less non-uniform size

and larger interface area of crystallization/amorphous

resulting in higher density of low and deep traps. It is deducd that the more complicated defect type in the interface can lead to broader distribution of trap depth and larger influence on the injection and movement of positive packet-like space charge.