中文摘要：

为研究温度场下非等温结晶对低密度聚乙烯（low-density polyethylene,LDPE）空间电荷特性的影响,制备了3种不同退火速率的非等温结晶试样即LDPE-I（冰水）、LDPE-A（空气）和LDPE-S（缓慢）,并使用温控脉冲电声（PEA）法开展了20℃、40℃和60℃温度场下空间电荷特性的研究。结果表明：非等温结晶过程中,更小的退火速率有利于LDPE充分结晶,因此结晶度更高、晶胞平均尺寸更大且尺寸均匀性更好;20℃温度和-100 MV/m直流电场强度条件下3组试样均出现正空间电荷包,LDPE-I电荷包注入速率和迁移速率均为最大;40℃和60℃温度下,仅在LDPE-I中存在正空间电荷包。针对上述现象,结合20℃温度下去极化过程载流子视在迁移率和陷阱深度情况进行解释：由于LDPE-I试样晶胞尺寸小且均匀性差,晶区/无定形区界面面积增加,所以深浅陷阱密度均增大;推测其界面缺陷类型复杂,导致陷阱深度分布广,从而对正空间电荷包的注入和迁移过程影响更大。

英文摘要：

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.