中文摘要：

为考察聚丙烯作为直流电缆绝缘材料在电气性能上的的可行性，选用等规聚丙烯材料制备测试试样，通过差示扫描量热法测试熔融温度（165℃）和结晶温度（111℃），针对击穿特性、强场电导和空间电荷分布与电荷的消散等电气性能对聚丙烯材料进行测试。击穿强度测试发现：其交流击穿强度明显低于直流击穿强度，交流击穿强度数据的的分散性相对于直流击穿要好。强场电导特性测试发现：在3.3kV／mm电场下当温度升高到90℃时，材料的强场电导明显升高，达到室温时的2倍。空间电荷实验结果表明聚丙烯在较低的电场强度（10、20kV／mm）下未出现明显的空间电荷，而在电场强度达到50kV／mm时，出现了明显的异极性空间电荷。将试样上下电极短接进行短路发现，10、20kV／mm下加压0．5h后，经过0．5h短路放电，试样内部的空间电荷几乎释放完全。而在50kV／mm下加压0．5h后，经过1．5h的短路时间仍然看到试样内部驻留着大量的异极性空间电荷。

英文摘要：

In order to evaluate the feasibility of electric performance in polypropylene（PP） as an insulation material for DC power cable, isotatic polypropylene was chosen to be prepared for investigating. The melting temperature（165 ℃） and crystallization temperature（111℃） were tested through differential scanning calorimetry （DSC）, and the electric perfor- mances such as breakdown strengths, electrical conductivity, distribution of space charge, and dissipate of space charge were tested for PP materials. It is revealed in the experiments of breakdown strengths that the AC breakdown strength（BDS） is lower than DC BDS, as well as the data dispersion of AC BDS is better than DC BDS. Through the measurement of high field conductivity, it is found that when the temperature increases to 90 ℃, the high field conductiv- ity of PP has an apparent increase and reaches twice of that at room temperature with the electrical field of 3.3 kV/mm. Space charge experiments with voltage show that no obvious space charge appears in PP under low electrical field strength （10 kV/mm and 20 kV/rnm）. A lot of hetero-charges appear in sample when the electrical field strength increases to 50 kV/mm. During the process of short circuit in space charge experiments, it is found that space charge in samples can be released completely in 0.5 h after applying an electrical field strength of 10 kV/mrn and 20 kV/mm for 0.5 h. However, when the process of short circuit lasts for 1.5 h, a lot of space charges still remain inside after applying the electrical field strengths of 50 kV/mm for 0.5 h.