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Effect of Crosslinking Degree on Tensile and Dielectric Properties of Cross-Linked Polyethylene/Organic Montmorillonite Nanocomposite Material |
Dong Yunzi, Gao Yuan, Li Xiufeng, Han Shengbin, Dong Ruixue |
College of Electrical and Electronic Engineering Shandong University of Technology Zibo 255000 China |
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Abstract Modification of polymers by nano-doping, regulation of the dispersion state of nanofillers in polymers, in order to improve the macroscopic properties of polymers have become hot research topics in the field of insulation. The crosslinking process of polymers also changes the state of nanoparticle dispersion and affects the bonding of the phase interface between nanoparticles and polymer matrix, resulting in differences in macroscopic properties. Montmorillonite (MMT) with its large length-to-thickness ratio can form a stable and solid interfacial zone with the polymer matrix, bind the movement of the molecular chain and block the charge, which can effectively improve the mechanical and electrical properties. Therefore, organic montmorillonite (OMMT) with a mass fraction of 0.5% was selected to modify PE, and cross-linked polyethylene/organic montmorillonite (XLPE/OMMT) nanocomposite with different crosslinking degrees were prepared by regulating the crosslinking time. The X-ray diffraction (XRD) test was used to determine the intercalation dispersion state of montmorillonite and the changes in the aggregated state structure of the specimens, and the scanning electron microscope (SEM) results were combined to analyze the changes of the crystalline morphology. The effects of the crosslinking degree on the tensile properties of XLPE/OMMT were analyzed in terms of plastic deformation and elastic deformation. The crosslinking degree of the dielectric properties of XLPE/OMMT was analyzed by using the conductance-temperature characteristics, dielectric constant and dielectric loss tangent test of the sample and the two-parameter Weibull distribution of power frequency breakdown field strength, combined with the crosslinking mesh structure and the interfacial properties of OMMT. The results of XRD show that OMMT reaches the exfoliated state in the XLPE/OMMT under the action of PE-g-MAH, and the crystallinity of the specimen decreases continuously with the increase of crosslinking time. The results from the gel content test show that the crosslinking degree of XLPE/OMMT increases and then decreases with the increase of crosslinking time, and reaches the maximum at 15~20min. It is concluded that XLPE/OMMT is in the state of "undercrosslinking" before crosslinking for 15min, "positive crosslinking" at 15~20min, and "over-crosslinking" after 20min. It is confirmed by SEM that the crosslinked network inhibits the crystal growth and the crystal size decreases with the increase of crosslinking time. Under the positive crosslinked state, the crystal size distribution is most uniform. The joint action of OMMT and crosslinked bonds improves the tensile strength, and the perfect crosslinked network increases the elastic modulus and enhances the toughness. The electrical conductivity of the specimens increased with temperature. The crosslinked network and the homogeneously distributed interfacial region increase the potential barrier and improve the activation energy. The increase of crosslinking degree forms a stronger intermolecular force, which hinders the turning polarization and decreases the dielectric constant and dielectric loss angle tangent; the addition of OMMT and the perfection of crosslinking structure together improve the breakdown field strength; however, excessive crosslinking increases the microscopic defects and decreases the breakdown field strength. The following conclusions can be drawn from the analysis of the experimental results: (1) The crosslinking degree of nanocomposites affects the uniformity of crystal size and crystallinity. However, the deterioration of dispersion of OMMT leads to an increase of crystal size difference during over-crosslinking. (2) The combination of crosslinked bonds, three-dimensional mesh structure and OMMT effectively improves the tensile strength and enhances the toughness and elastic modulus of the material. (3) The electrical conductivity of nanocomposites is closely related to its crosslinking degree and the interfacial force formed by OMMT and the matrix. In the positive crosslinking state, the combined effects of the crosslinked bonds and interfacial results in the decrease of dielectric constant and dielectric loss tangent of the composites. The integrity of the microstructure of the composite promoted by proper crosslinking and the barrier effect of OMMT improve the electrical strength of the composites.
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Received: 30 June 2022
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[1] 王昊月, 王晓威, 孙茂伦, 等. XLPE电缆绝缘热老化的高压频域介电谱诊断方法[J]. 电工技术学报, 2022, 37(17): 4497-4507. Wang Haoyue, Wang Xiaowei, Sun Maolun, et al.Research progress in the UV-initiated polyethylene cross-linking technology[J]. Transactions of China Electrotechnical Society, 2022, 37(17): 4497-4507. [2] 李宗辉, 陈林艳, 陈艺伟. 10kV交联聚乙烯电缆绝缘老化超低频介损试验的研究[J]. 电气技术, 2020, 21(10): 83-87. Li Zonghui, Chen Linyan, Chen Yiwei.Study on ultra-low frequency dielectric loss detection of 10kV cross-linked polyethylene aged cable[J]. Electrical Engineering, 2020, 21(10): 83-87. [3] 李厚玉, 李长明, 孙伟峰. 紫外光引发聚乙烯交联技术研究进展[J]. 电工技术学报, 2020, 35(15): 3356-3367. Li Houyu, Li Changming, Sun Weifeng.Research progress in the UV-initiated polyethylene cross-linking technology[J]. Transactions of China Electrotechnical Society, 2020, 35(15): 3356-3367. [4] Yan Zhimin, Yang Kai, Zhang Yuanyuan, et al.Crosslinking dependence of trap distribution and breakdown performance of crosslinked polyethylene[J]. Journal of Materials Science: Materials in Electronics, 2019, 30(23): 20605-20613. [5] 张桥峰, 周凯, 李康乐, 等. 不同交联温度下交联聚乙烯绝缘中的水树生长特性研究[J]. 中国电机工程学报, 2021, 41(16): 5758-5767. Zhang Qiaofeng, Zhou Kai, Li Kangle, et al.Study the growth characteristic of water trees in XLPE insulation at different crosslinking temperatures[J]. Proceedings of the CSEE, 2021, 41(16): 5758-5767. [6] 张桥峰, 周凯, 李康乐, 等. 交联度对交联聚乙烯时域介电特性的影响[J]. 绝缘材料, 2020, 53(12): 27-31. Zhang Qiaofeng, Zhou Kai, Li Kangle, et al.Effect of crosslinking degree on time domain dielectric properties of XLPE[J]. Insulating Materials, 2020, 53(12): 27-31. [7] 袁宝, 毛应涛, 李维康, 等. 助交联剂对过氧化物交联聚乙烯绝缘料性能的影响[J]. 绝缘材料, 2020, 53(5): 34-40. Yuan Bao, Mao Yingtao, Li Weikang, et al.Effect of co-crosslinking agent on properties of peroxide crosslinked polyethylene insulating material[J]. Insulating Materials, 2020, 53(5): 34-40. [8] 周湶, 伍能成, 廖瑞金, 等. 不同交联程度交联聚乙烯的空间电荷特征[J]. 高电压技术, 2013, 39(2): 294-301. Zhou Quan, Wu Nengcheng, Liao Ruijin, et al.Space charge characteristics of cross-linked polyethylene with different cross-linking degrees[J]. High Voltage Engineering, 2013, 39(2): 294-301. [9] 杨云梦, 许庆重, 邓繁盛, 等. XLPE/OMMT纳米复合电介质力学性能和水树枝特性研究[J]. 绝缘材料, 2021, 54(8): 45-51. Yang Yunmeng, Xu Qingzhong, Deng Fansheng, et al.Mechanical properties and water tree characteristics of XLPE/OMMT nanocomposite dielectrics[J]. Insulating Materials, 2021, 54(8): 45-51. [10] Lim K S, Mariatti M, Kamarol M, et al.Properties of nanofillers/crosslinked polyethylene composites for cable insulation[J]. Journal of Vinyl and Additive Technology, 2019, 25(S1): E147-E154. [11] Said A, Nawar A G, Eldesoky E A, et al.Enhancing the high voltage XLPE cable insulation characteristics using functionalized TiO2 nanoparticles[J]. American Journal of Polymer Science and Technology, 2020, 6(3): 21-31. [12] 李盛涛, 谢东日, 闵道敏. 聚丙烯/Al2O3纳米复合介质直流击穿特性与电荷输运仿真研究[J]. 中国电机工程学报, 2019, 39(20): 6122-6130, 6193. Li Shengtao, Xie Dongri, Min Daomin.Numerical simulation on space charge transport and DC breakdown properties of polypropylene/Al2O3 nanocomposites[J]. Proceedings of the CSEE, 2019, 39(20): 6122-6130, 6193. [13] 雷伟群, 刘冠芳, 耿涛, 等. XLPE/SiO2纳米复合材料长期直流老化特征寿命恶化分析[J]. 电工技术学报, 2022, 37(2): 311-321. Lei Weiqun, Liu Guanfang, Geng Tao, et al.Analysis on the characteristic lifetime deterioration of XLPE/SiO2 nano-composites after long-term DC aging[J]. Transactions of China Electrotechnical Society, 2022, 37(2): 311-321. [14] 张晓虹, 石泽祥, 张双, 等. 基于局部放电特征研究蒙脱土/聚乙烯纳米复合材料的电树枝性能[J]. 电工技术学报, 2019, 34(23): 5049-5057. Zhang Xiaohong, Shi Zexiang, Zhang Shuang, et al.Investigation on electrical tree resistance property of montmorillonite/polyethylene nanocomposites based on partial discharge characteristics[J]. Transactions of China Electrotechnical Society, 2019, 34(23): 5049-5057. [15] 李果, 李秀峰, 申晋, 等. 交联行为对纳米复合电介质电导特性和电气强度的影响[J]. 绝缘材料, 2019, 52(3): 25-30, 35. Li Guo, Li Xiufeng, Shen Jin, et al.Effect of crosslinking behavior on conductivity characteristics and electric strength of nanocomposite dielectrics[J]. Insulating Materials, 2019, 52(3): 25-30, 35. [16] 李秀峰, 彭云舜, 咸日常, 等. XLPE/OMMT纳米复合材料电导和击穿性能[J]. 高电压技术, 2017, 43(9): 2849-2856. Li Xiufeng, Peng Yunshun, Xian Richang, et al.Conductivity and breakdown properties on cross-linked polyethylene/montmorillonite nanocomposites[J]. High Voltage Engineering, 2017, 43(9): 2849-2856. [17] 李秀峰, 咸日常, 杨培杰, 等. 有机插层剂对交联聚乙烯/OMMT纳米复合电介质机械性能与热稳定性的影响[J]. 塑料工业, 2016, 44(11): 143-147. Li Xiufeng, Xian Richang, Yang Peijie, et al.The influence of organic intercalants on mechanical properties and thermostability of crosslinked PP/OMMT nanocomposite dielectrics[J]. China Plastics Industry, 2016, 44(11): 143-147. [18] 罗兵, 孟繁博, 王婷婷, 等. 脱气处理对高压直流电缆绝缘特性的影响[J]. 电工技术学报, 2021, 36(增刊2): 730-735. Luo Bing, Meng Fanbo, Wang Tingting, et al.Effect of degassing treatments on insulation characteristics of high voltage DC cables[J]. Transactions of China Electrotechnical Society, 2021, 36(S2): 730-735. [19] 王彦峰, 闫国兵, 谢榕昌, 等. 电热联合老化对XLPE电缆绝缘特性的影响[J]. 电力工程技术, 2021, 40(5): 128-135. Wang Yanfeng, Yan Guobing, Xie Rongchang, et al.Effect of electro-thermal aging on characteristics of XLPE cable insulation[J]. Electric Power Engineering Technology, 2021, 40(5): 128-135. [20] 梁英, 陈逸昕, 刘云鹏. 运行复合绝缘子材料的体积电阻率-温度特性研究[J]. 电工技术学报, 2014, 29(10): 312-317. Liang Ying, Chen Yixin, Liu Yunpeng.Research on characteristics of volume-resistivity and temperature for field composite insulators[J]. Transactions of China Electrotechnical Society, 2014, 29(10): 312-317. [21] 来金雅, 温变英. 不同主链马来酸酐接枝物对PP/OMMT纳米复合材料增容效果的对比[J]. 高分子材料科学与工程, 2012, 28(10): 94-98. Lai Jinya, Wen Bianying.Comparison of effetiveness of two maleic anhydride grafted polymer for the compatibilization of PP/OMMT composites[J]. Polymer Materials Science & Engineering, 2012, 28(10): 94-98. [22] 李康乐, 周凯, 张桥峰, 等. 水树生长早期的XLPE晶区破坏现象及机制[J]. 中国电机工程学报, 2021, 41(24): 8631-8643. Li Kangle, Zhou Kai, Zhang Qiaofeng, et al.Damage phenomenon and mechanism of XLPE crystalline region in the early propagation period of water trees[J]. Proceedings of the CSEE, 2021, 41(24): 8631-8643. [23] Yang Zhangyong, Li Huan, Duan Yilin, et al.Study on melting characteristics of crystals in thermal aged XLPE cable insulation at elevated temperature[J]. Journal of Materials Science: Materials in Electronics, 2021, 32(12): 16194-16202. [24] 谢大荣, 巫松桢. 电工高分子物理[M]. 西安: 西安交通大学出版社, 1990. [25] Li Shengtao, Min Daomin, Wang Weiwang, et al.Linking traps to dielectric breakdown through charge dynamics for polymer nanocomposites[J]. IEEE Transactions on Dielectrics and Electrical Insulation, 2016, 23(5): 2777-2785. [26] 于钦学, 任文娥. 电气绝缘实验与分析[M]. 西安: 西安交通大学出版社, 2013. [27] 胥智勇, 赵洪, 陈俊岐, 等. 交联度对交联聚乙烯水树枝老化特性的影响[J]. 绝缘材料, 2017, 50(4): 31-35, 41. Xu Zhiyong, Zhao Hong, Chen Junqi, et al.Influence of crosslinking degree on water treeing of crosslinked polyethylene[J]. Insulating Materials, 2017, 50(4): 31-35, 41. [28] (澳)米耀荣, 于中振. 聚合物纳米复合材料[M]. 杨彪, 译. 北京: 机械工业出版社, 2010. [29] 张福增, 李淑琦, 朱永华, 等. 热老化对挤塑绝缘XLPE直流电缆空间电荷特性的影响[J]. 绝缘材料, 2015, 48(8): 41-45. Zhang Fuzeng, Li Shuqi, Zhu Yonghua, et al.Influence of thermal ageing on space charge characteristics of extruded XLPE HVDC cable[J]. Insulating Materials, 2015, 48(8): 41-45. [30] 刘孟佳, 周福升, 陈铮铮, 等. 采用等温表面电位衰减法表征LDPE与HDPE内陷阱的分布特性[J]. 中国电机工程学报, 2016, 36(1): 285-291. Liu Mengjia, Zhou Fusheng, Chen Zhengzheng, et al.Characterizing trap distribution in LDPE and HDPE based on isothermal surface potential decay measurement[J]. Proceedings of the CSEE, 2016, 36(1): 285-291. [31] 许庆重, 李秀峰, 邓繁盛, 等.交联行为对XLPE/OMMT纳米复合材料结构和介电性能的影响[J/OL]. 中国电机工程学报: 1-10 [2022-10-28]. DOI: 10.13334/j.0258-8013.pcsee.212247. Xu Qingzhong, Li Xiufeng, Deng Fansheng, et al.Effect of crosslinking behavior on the structure and dielectric properties of XLPE/OMMT nanocom-posites[J/OL]. Proceedings of the CSEE: 1-10 [2022-08-10]. DOI:10.13334/j.0258-8013.pcsee. 212247. [32] Chen Jie, Zhang Wei, Ding Man, et al.Aging characteristics of XLPE insulation of 110 kV cables in the initial stage of operation[J]. Energy Engineering, 2021, 118(5): 1537-1548. [33] 李秀峰, 咸日常, 胡元潮, 等. 有机插层剂对纳米复合材料介电性能的影响[J]. 山东理工大学学报(自然科学版), 2017, 31(5): 29-34. Li Xiufeng, Xian Richang, Hu Yuanchao, et al.The influence of organic intercalants on dielectric properties of crosslinked polyethylene/montmorillonite nano-composite[J]. Journal of Shandong University of Technology (Natural Science Edition), 2017, 31(5): 29-34. [34] 秦福宁, 邵光磊, 张忠蕾, 等. 电缆中间接头硅橡胶绝缘的理化特性研究[J]. 绝缘材料, 2020, 53(12): 44-49. Qin Funing, Shao Guanglei, Zhang Zhonglei, et al.Physical and chemical characteristics of silicone rubber insulation for cable intermediate joint[J]. Insulating Materials, 2020, 53(12): 44-49. [35] 曹海盛, 谢从珍, 王瑞, 等. 基于三相联合分析的XLPE温度频变热老化研究[J]. 绝缘材料, 2020, 53(8): 75-81. Cao Haisheng, Xie Congzhen, Wang Rui, et al.Study on temperature frequency-variable thermal ageing of XLPE based on three-phase joint analysis[J]. Insulating Materials, 2020, 53(8): 75-81. [36] 刘衍, 周求宽, 赵晶轩, 等. 交互区对纳米Al2O3-环氧树脂复合电介质短时击穿特性的影响[J]. 西安交通大学学报, 2016, 50(12): 18-23, 154. Liu Yan, Zhou Qiukuan, Zhao Jingxuan, et al.Effect of interaction zone on short-time breakdown of nanoAl2O3-epoxy composites[J]. Journal of Xi'an Jiaotong University, 2016, 50(12): 18-23, 154. [37] 金维芳. 电介质物理学[M]. 2版. 北京: 机械工业出版社, 1997. [38] Li Guochang, Zhou Xuguang, Li Xuejing, et al.DC breakdown characteristics of XLPE/BNNS nanocom-posites considering BN nanosheet concentration, space charge and temperature[J]. High Voltage, 2020, 5(3): 280-286. |
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