不同交联程度交联聚乙烯的空间电荷特征

Space Charge Characteristics of Cross-linked Polyethylene with Different Cross-linking Degrees

为研究交联程度对聚乙烯空间电荷特征的影响,选用过氧化二异丙苯为交联剂并以低密度聚乙烯为基料,制备了交联程度不同的交联聚乙烯试样,分别对各试样进行了电荷注入阈值电场强度试验、加压时空间电荷累积试验和去压时空间电荷消散试验。然后以平均电荷密度为特征参量,分析了加压试验和消散试验中的空间电荷分布图谱,获得了交联程度对低密度聚乙烯空间电荷特征的影响。结果表明:交联向聚乙烯中引入了负电荷陷阱,并且增加了较深电荷陷阱的密度;交联能够显著提高聚乙烯的电荷注入阈值电场强度,其中氧化二异丙苯质量分数为3%样品的阈值电场强度最高;交联使得加压时电荷不易注入,而去压后当电场强度较低时电荷主要分布于电极附近,电场强度较高时电荷分布较深。

We experimentally study the influence of cross-linking degree on space charge property of polyethylene.Selecting dicumyl peroxide（DCP） and low density polyethylene（LDPE） as different cross-linking degree samples,we measured space charge of each sample by a voltage ramp test to find the threshold electric field strength on which a bulk charge starts to accumulate.Following ramp test,space charge measurements were carried out at regular intervals when the external voltage was applied,and then space charge decay was tested by recording the space charge profile at different time intervals after the removal of applied voltage.By analyzing the space charge profiles of the experiments,some results are obtained as follows.Cross-linking will introduce negative charge traps to LDPE,and increase the density of deeper charge traps.Cross-linking can significantly raise the threshold electric field strength of LDPE：the strength has the highest value when the DCP content is 3%.Cross-linking makes the charge injection harder when voltage is applied.Charge mainly distributes near the electrode in the decay test when the applied electric field strength is low,and the distribution becomes deeper when the applied voltage is comparatively high.