Abstract：Ethylene propylene diene monomer (EPDM) reinforced insulation, as a crucial component of high voltage cable accessory, suffers from severe discharge at the insulation interface between EPDM and cross-linked polyethylene (XLPE) insulation, which threatens the stable operation of power cable and limits the increase of its voltage level. Therefore, it is essential to increase the insulation performance of the EPDM/XLPE interface. Currently, there are two engineering methods to enhance the interface breakdown strength, namely increasing interface pressure and coating the interface with silicone grease. However, both the two methods have their drawbacks. Excessive interface pressure may lead to microcracks in the rubber, and the silicone grease coating on the interface may cause swelling of the rubber, preventing the long-term maintenance of high insulation strength and accelerating electrical tree degradation in the rubber-reinforced insulation. Voltage stabilizers are often used to improve the electrical tree resistance of polymers, and also have an enhancing effect on the breakdown strength of polymers. However, it is unclear whether voltage stabilizer can be used to improve the surface properties of polymer insulation. In this paper, to enhance the insulation performance of the EPDM/XLPE interface, a surface liquid-infiltrating-grafting method was proposed to modify the EPDM surface by grafting voltage stabilizer 4-acryloxy-2-hydroxybenzophenone (AOHBP) onto the surface of EPDM sample. The AC and DC breakdown strength of the EPDM/XLPE interface, surface conductivity, space charge behavior and surface trap distribution of EPDM were analyzed before and after modification. Firstly, physical and chemical characterization was performed on the samples before and after modification. Fourier transform infrared spectroscopy was used to confirm whether the voltage stabilizer AOHBP was successfully grafted onto the EPDM molecular chain. Scanning electron microscopy was employed to observe the surface morphology of each sample and assess the impact of modification on the surface morphology of the sample. Next, surface conductivity, space charge behavior and AC and DC breakdown strength of the EPDM/XLPE interface were tested for the samples before and after modification to explore the impact of grafting modification on the electrical properties of the EPDM surface and EPDM/XLPE interface. Finally, surface potential decay was conducted on samples before and after modification to analyze the impact of grafting modification on the surface trap distribution of EPDM. Then the mechanism of grafted AOHBP enhancing the insulation performance of the EPDM/XLPE interface was analyzed. The results indicate that using dicumyl peroxide (DCP) as an initiator can successfully graft the voltage stabilizer AOHBP onto the EPDM molecular chain, and the grafting modification does not affect the surface morphology of EPDM. Grafting AOHBP introduces a new shallow trap dominated trap mechanism to the EPDM surface, effectively increasing the surface conductivity of EPDM, improving its space charge behavior, suppressing electric field distortion, and significantly enhancing the AC and DC breakdown strength of the EPDM/XLPE interface. Analysis of the experimental results led to the following conclusions: (1) The results of fourier transform infrared spectroscopy and scanning electron microscopy show that the surface liquid-infiltrating-grafting method realizes the grafting modification of the voltage stabilizer AOHBP on the layer of EPDM, and the microscopic morphology of the EPDM surface is not changed during the grafting process, and the grafting depth and grafting rate of the EPDM surface increase with the increase of DCP. (2) Grafting the voltage stabilizer AOHBP onto the EPDM surface can effectively increase the AC and DC breakdown strength of the EPDM/XLPE interface and provide some suppression of filed distortion caused by space charge. (3) The voltage stabilizer AOHBP can eliminate high-energy electrons, thus suppressing collision ionizations and electron avalanches on the EPDM/XLPE interface and enhancing the interface insulation performance.
纪多, 李春阳, 杨旭, 金永兴, 邵满智, 赵洪. 表面接枝电压稳定剂改善三元乙丙橡胶界面绝缘性能[J]. 电工技术学报, 2025, 40(15): 4941-4953.
Ji Duo, Li Chunyang, Yang Xu, Jin Yongxing, Shao Manzhi, Zhao Hong. Enhanced Interface Insulation Performance of EPDM by Surface Grafting of Voltage Stabilizer. Transactions of China Electrotechnical Society, 2025, 40(15): 4941-4953.
[1] 惠宝军, 傅明利, 刘通, 等. 110 kV及以上电力电缆系统故障统计分析[J]. 南方电网技术, 2017, 11(12): 44-50, 67. Hui Baojun, Fu Mingli, Liu Tong, et al.Statistical analysis on failures of 110 kV and above power cable system[J]. Southern Power System Technology, 2017, 11(12): 44-50, 67. [2] 刘昌, 惠宝军, 傅明利, 等. 机械应力对硅橡胶高压电缆附件运行可靠性的影响[J]. 高电压技术, 2018, 44(2): 518-526. Liu Chang, Hui Baojun, Fu Mingli, et al.Influence of mechanical stress on the operation reliability of silicone rubber high voltage cable accessories[J]. High Voltage Engineering, 2018, 44(2): 518-526. [3] Suh K S, Nam J H, Kim J H, et al.Interfacial properties of XLPE/EPDM laminates[J]. IEEE Transactions on Dielectrics and Electrical Insulation, 2000, 7(2): 216-221. [4] Ross R.Dealing with interface problems in polymer cable terminations[J]. IEEE Electrical Insulation Magazine, 1999, 15(4): 5-9. [5] Zhu Bin, Jia Zhidong, Hu Hao, et al.Interface resistivity and interfacial DC breakdown voltage of double-layer dielectrics[J]. IEEE Transactions on Dielectrics and Electrical Insulation, 2019, 26(4): 1181-1189. [6] 王霞, 余栋, 张宇巍, 等. 硅脂涂覆料对XLPE/ EPDM复合介质界面电荷积聚和击穿特性的影响[J]. 中国电机工程学报, 2018, 38(14): 4281-4287, 4334. Wang Xia, Yu Dong, Zhang Yuwei, et al.Effect of coating silicone grease on charge accumulation and breakdown strength at XLPE/EPDM interface[J]. Proceedings of the CSEE, 2018, 38(14): 4281-4287, 4334. [7] 王霞, 王华楠, 陈飞鹏, 等. 电晕放电加速硅脂劣化对硅橡胶绝缘表面性能的影响[J]. 高电压技术, 2020, 46(11): 3977-3985. Wang Xia, Wang Huanan, Chen Feipeng, et al.Effect of corona-discharge-accelerated deterioration of silicone grease on the surface properties of silicone rubber insulation[J]. High Voltage Engineering, 2020, 46(11): 3977-3985. [8] 胡巍, 赵洪, 牛越, 等. 高压电缆附件用橡胶基增强绝缘电学性能研究进展[J]. 绝缘材料, 2021, 54(7): 1-9. Hu Wei, Zhao Hong, Niu Yue, et al.Research progress on electrical properties of rubber-based reinforced insulation for high voltage cable accessories[J]. Insulating Materials, 2021, 54(7): 1-9. [9] Liao Yanqun, Yang Kai, Yan Zhimin, et al.Effect of silicone grease on electrical tree degradation of silicon rubber under AC electric field[J]. Journal of Materials Science: Materials in Electronics, 2020, 31(8): 6279-6287. [10] Wang Xia, Wang Chencheng, Wu Kai, et al.An improved optimal design scheme for high voltage cable accessories[J]. IEEE Transactions on Dielectrics and Electrical Insulation, 2014, 21(1): 5-15. [11] Li Chunyang, Zhang Chengcheng, Zhao Hong, et al.Voltage stabilizer and its effects on polymer's DC insulation performance[M]//Du Boxue. Polymer Insulation Applied for HVDC Transmission. Singapore: Springer Singapore, 2020: 45-75. [12] Li Chunyang, Zhang Chengcheng, Zhao Hong, et al.Grafted UV absorber as voltage stabilizer against electrical degradation and breakdown in cross-linked polyethylene for high voltage cable insulation[J]. Polymer Degradation and Stability, 2021, 185: 109498. [13] 李春阳, 陈先胜, 胡巍, 等. 电压稳定剂对电缆附件三元乙丙橡胶本体与绝缘界面耐电性能影响[J]. 中国电机工程学报, 2023, 43(13): 5281-5294. Li Chunyang, Chen Xiansheng, Hu Wei, et al.Effects of voltage stabilizers on the body and interface electrical strengths of EPDM for cable accessory[J]. Proceedings of the CSEE, 2023, 43(13): 5281-5294. [14] 陈向荣, 黄小凡, 王启隆, 等. 电压稳定剂接枝改性对500 kV直流XLPE电缆材料电气性能的影响[J]. 电工技术学报, 2024, 39(1): 23-33. Chen Xiangrong, Huang Xiaofan, Wang Qilong, et al.Effect of voltage stabilizer grafting on electrical properties of 500 kV DC XLPE cable insulation materials[J]. Transactions of China Electrotechnical Society, 2024, 39(1): 23-33. [15] 陈向荣, 洪泽林, 朱光宇, 等. 高温下电压稳定剂对交联聚乙烯电树枝化及局部放电特性的影响[J]. 电工技术学报, 2023, 38(3): 577-586. Chen Xiangrong, Hong Zelin, Zhu Guangyu, et al.Effect of voltage stabilizer on electrical treeing and partial discharge characteristics of crosslinked polyethylene at high temperature[J]. Transactions of China Electrotechnical Society, 2023, 38(3): 577-586. [16] 石逸雯, 陈向荣, 孟繁博, 等. 电压稳定剂及其含量对高压直流用500kV XLPE电缆材料绝缘性能的影响[J]. 电工技术学报, 2022, 37(22): 5851-5861. Shi Yiwen, Chen Xiangrong, Meng Fanbo, et al.The effect of voltage stabilizer and its content on the insulation properties of 500kV HVDC cable insulation materials[J]. Transactions of China Electrotechnical Society, 2022, 37(22): 5851-5861. [17] 谢庆, 张采芹, 闫纪源, 等. 不均匀直流电场下绝缘材料表面电荷积聚与消散特性[J]. 电工技术学报, 2019, 34(4): 817-830. Xie Qing, Zhang Caiqin, Yan Jiyuan, et al.Study on accumulation and dissipation of surface charges of insulating materials under uneven DC field[J]. Transactions of China Electrotechnical Society, 2019, 34(4): 817-830. [18] Das-Gupta D K. Electrical properties of surfaces of polymeric insulators[J]. IEEE Transactions on Electrical Insulation, 1992, 27(5): 909-923. [19] Wintle H J.Decay of surface electric charge in insulators[J]. Japanese Journal of Applied Physics, 1971, 10(5): 659. [20] Molinie P.A review of mechanisms and models accounting for surface potential decay[J]. IEEE Transactions on Plasma Science, 2012, 40(2): 167-176. [21] Llovera P, Molinie P.New methodology for surface potential decay measurements: application to study charge injection dynamics on polypropylene films[J]. IEEE Transactions on Dielectrics and Electrical Insulation, 2004, 11(6): 1049-1056. [22] Watson P K.The transport and trapping of electrons in polymers[J]. IEEE Transactions on Dielectrics and Electrical Insulation, 1995, 2(5): 915-924. [23] 李志辉, 解曾祺, 李庆民, 等. 多巴胺接枝的纳米氮化硼改性环氧树脂绝缘表面电荷高频消散特性[J]. 电工技术学报, 2023, 38(5): 1116-1128. Li Zhihui, Xie Zengqi, Li Qingmin, et al.Study on the surface charge dissipation characteristics of epoxy resin modified by dopamine grafted nano boron nitride under high frequency electric stress[J]. Transactions of China Electrotechnical Society, 2023, 38(5): 1116-1128. [24] Simmons J G, Tam M C.Theory of isothermal currents and the direct determination of trap parameters in semiconductors and insulators containing arbitrary trap distributions[J]. Physical Review B, 1973, 7(8): 3706-3713. [25] Simmons J G, Taylor G W, Tam M C.Thermally stimulated currents in semiconductors and insulators having arbitrary trap distributions[J]. Physical Review B, 1973, 7(8): 3714-3719. [26] Yuan Hao, Zhou Yao, Zhu Yujie, et al.Origins and effects of deep traps in functional group grafted polymeric dielectric materials[J]. Journal of Physics D: Applied Physics, 2020, 53(47): 475301.
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