共查询到18条相似文献,搜索用时 203 毫秒
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茂金属聚乙烯改性低密度聚乙烯中空间电荷的机理研究 总被引:10,自引:3,他引:10
针对高压,超高压直流塑料电缆中存在的空间电荷效应,文中选用与普通低密度聚乙烯(LDPE)化学结构相似的茂金属聚乙烯(MPE)作为成核剂与LDPE共混,用电声脉冲法(PEA)测量了共混物的空间电荷特性,以差示扫描量热法(DSC)研究了共混物的非等温结晶行为,用高阻计测量了共混物的体积电阻率的变化,结合聚合物的结晶和导电理论,讨论了共混物中空间电荷的形成和抑制机理。测试结果表明:1%的MPE与LDPE共混,能有效降低LDPE中空间电荷效应,提高结晶温度,降低体积电阻率。 相似文献
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聚乙烯类材料因其优异的介电性能被广泛应用于高压直流电缆绝缘。直流电缆运行过程中,绝缘材料电导率随温度梯度变化和直流电场下空间电荷的积聚而变化,导致绝缘材料内部电场畸变,是目前高压直流聚乙烯电缆绝缘发展面临的严峻问题。该文通过综合国内外研究,论述了高压直流电缆聚乙烯绝缘材料的研究进展,分析了改性聚乙烯绝缘材料的介电性能和作用机理,最后展望了高压直流聚乙烯绝缘材料的发展趋势。研究结果表明,纳米掺杂改性能够有效抑制聚乙烯绝缘材料内部空间电荷的积累,改善聚乙烯绝缘材料直流电导率的温度特性;共混改性生产免交联的聚乙烯绝缘材料能够提高其介电性能;电压稳定剂能提高聚乙烯绝缘材料的耐电树枝性能,具有良好的发展前景;超纯净聚乙烯绝缘材料是高压直流聚乙烯电缆绝缘材料研发的基础和重点。这些研究成果的总结可为未来高压直流电缆聚乙烯绝缘材料的研究和发展提供参考。 相似文献
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《绝缘材料》2017,(9)
为研究温度对直流电缆用交联聚乙烯绝缘性能的影响,选取了2种具有代表性的直流电缆用交联聚乙烯和1种交流电缆用交联聚乙烯进行对比研究。分别对其在不同温度下的直流电导率和空间电荷集聚特性进行分析。结果表明:在温度范围为20~70℃时,3种交联聚乙烯试样的直流电导率随着温度的升高呈指数增大,但电导活化能有差异,直流电缆用交联聚乙烯的电导率随温度升高的变化程度较小;交流电缆用交联聚乙烯以积聚负电荷占主导,而2种直流电缆用交联聚乙烯空间电荷的平均电荷密度较小。此外,3种材料在常温下的直流击穿场强差异明显;红外光谱结果表明直流电缆用交联聚乙烯具有更少的羰基基团。2种直流电缆用交联聚乙烯分别采用提高纯净度和引入无机填料2种方式,使直流介电性能得到了改善。 相似文献
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由于高压直流塑料电缆运行中温度梯度效应会引起场强畸变,选用一种特殊的纳米粒子作为填料,通过熔融共混制备出不同填料质量分数(1%,3%,5%)的低密度聚乙烯(LDPE)纳米复合材料。通过扫描电镜(SEM)观察,证明纳米粒子在聚乙烯中分散均匀。利用电声脉冲(PEA)法研究了温度梯度场下LDPE纳米复合材料中的空间电荷及场强畸变特性;并测量了不同温度下的体积电阻率和直流击穿特性。结果表明,该种纳米粒子的添加能有效改善温度梯度场下聚乙烯绝缘中电荷积聚和场强的畸变现象,并提高聚乙烯的直流击穿强度。同时发现,该聚乙烯纳米复合材料体积电阻率随着温度升高呈现先升后降趋势。 相似文献
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《高电压技术》2018,(12)
为探索提升高压直流电缆用交联聚乙烯直流介电性能的方法,采用熔融共混法在直流电缆用交联聚乙烯基体中添加微量(质量分数0.1%、0.5%、1%)纳米TiO_2制备得到XLPE/TiO_2纳米复合介质,并通过纳米粒子表面偶联剂处理对比研究了表面改性对XLPE/TiO_2介电性能的影响。采用SEM观测纳米粒子的分散性,测试了XLPE和XLPE/TiO_2的结晶度、电导率温度特性、空间电荷注入特性和直流击穿场强。结果表明,采用偶联剂进行表面处理能够改善纳米粒子的分散性,在直流电缆用XLPE中直接添加微量纳米TiO_2能够增大结晶度、电导活化能和直流击穿场强,降低电导率,抑制正电荷的注入,而添加经过偶联剂处理的纳米TiO_2可使这些影响更加显著。分析认为,结晶度的增大是由于纳米粒子的成核作用,而偶联剂处理使得粒子与基体结合更加紧密从而进一步增大结晶度。电导特性和空间电荷特性的改善主要由于纳米TiO_2形成交互区以及聚集态结构改变对陷阱特性的影响,在较低场强下测试得到的电导活化能的增大即对应为复合介质的深陷阱能级的增加,因此电荷注入得到了明显的抑制。电荷陷阱的引入也使得电导率随粒子含量的增加而减小。直流击穿场强的提高则是由聚集态结构和陷阱特性两者共同作用导致的。因此,高压直流电缆用交联聚乙烯材料可以采用添加微量纳米TiO_2(0.5%)进一步改善直流介电性能,偶联剂处理过程则使得改善效果更加显著。 相似文献
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Wang X. He H.Q. Tu D.M. Lei C. Du Q.G. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2008,15(2):319-326
Dielectric properties of low-density polyethylene (LDPE) blended with metallocene catalyzed polyethylene (MPE) to 1, 3, 5 wt% of the latter are reported. It was found that the 1 wt% MPE blend had the lowest volume resistivity, the highest direct current (DC) breakdown strength and the least accumulated space charge. The crystalline morphology of the blends was studied through differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and small-angle light scattering (SALS) measurements. It was found that blending increased the percentage crystallinity, decreased the spherulite size and caused the formation of imperfect spherulites, i.e. spherulites containing defects and impurities in their crystalline phases, and thus fewer impurities and defects on their boundaries. The improvement in dielectric properties of the blends, especially the 1 wt% MPE blend, is attributed to the increase in crystallinity and the formation of imperfect spherulites. 相似文献
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空间电荷对低密度聚乙烯电气击穿特性的影响 总被引:5,自引:3,他引:2
为解决聚乙烯用作电线电缆绝缘材料时所受空间电荷问题的困扰,采用在低密度聚乙烯(low density po-lyethylene,LDPE)试品上施加直流预电压使其中积聚一定量的空间电荷,然后测量试品击穿强度的方法,研究了空间电荷对LDPE击穿特性的影响。结果表明,与未经过预电压处理的LDPE的击穿强度相比,在经过较低场强(50 kV/mm)预电压处理后,预电压与击穿电压极性相同时击穿强度提高了约9%,极性相异时击穿强度降低约14%;而经过较高场强(150 kV/mm)预电压处理后,预电压时LDPE中出现空间电荷包现象,预电压后同极性击穿强度提高约19%,而异极性击穿强度反而上升约16%。分析认为空间电荷包在LDPE中的运动导致了部分空间电荷的中和,使得空间电荷积聚量减少,同时LDPE中可能的缺陷得到了一定程度的老炼而使介质得到了均匀化,从而使LDPE的击穿强度得到了提高。 相似文献
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纳米ZnO/低密度聚乙烯复合材料的介电特性 总被引:3,自引:0,他引:3
聚合物纳米复合材料因其优良的介电、机械等性能在电介质领域得到广泛的应用。纳米粒子改性聚乙烯基绝缘材料具有很好的研究价值及工程意义。该文主要研究了表面经分散剂处理的纳米ZnO粒子添加剂与低密度聚乙烯(LDPE)共混物的介电特性。结果表明5%含量的纳米ZnO添加剂能有效提高聚乙烯基复合材料的体积电阻率和交流击穿强度。同时纳米添加剂虽增加了体内的残余电荷,但能有效抑制电极同极性电荷的注入。另外由于聚合物纳米复合材料的界面特异性,使得介电常数随着纳米ZnO含量的增加呈先减小后增大趋势,而损耗值却线性增加。纳米ZnO/聚乙烯复合材料介电性能提高归因于纳米粒子与聚乙烯分子间类同于深陷阱的界面效应。 相似文献
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Murakami Y. Nemoto M. Okuzumi S. Masuda S. Nagao M. Hozumi N. Sekiguchi Y. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2008,15(1):33-39
To understand basic electric properties of nano-sized magnesium oxide (MgO) / low-density polyethylene (LDPE) nanocomposite under DC voltage application, the volume resistivity, the space charge distribution and the breakdown strength were investigated. By the addition of nano-sized MgO filler, both the DC breakdown strength and the volume resistivity of LDPE increased. At the average DC electric field of about 85 kV/mm and more, a positive packet space charge was observed in LDPE without MgO nano-filler, whereas a little homogeneous space charge was observed in MgO/LDPE nanocomposite material at the front of electrode. From these results, it is confirmed that the addition of MgO nano-filler leads to the improvement of DC electrical insulating properties of LDPE. 相似文献
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Shaoqing Chen Zongren Peng Xia Wang Xia Cheng 《IEEJ Transactions on Electrical and Electronic Engineering》2011,6(1):7-13
In this paper, space charge distributions as well as dielectric properties, such as volume resistivity and AC breakdown strength, were studied in low‐density polyethylene (LDPE) and its composite obtained by adding nano‐ZnO nanofiller, before and after photo‐oxidation or corona aging for several days. It was found that a small amount of ZnO nanoparticles could effectively improve both the photostabilization and corona stabilization of the LDPE matrix. Fourier transform infrared (FTIR) spectra of the specimens were investigated to reveal the change of the microstructures. The results showed that a weaker carbonyl absorption peak appeared in LDPE/ZnO nanocomposite than in LDPE. A proper explanation is given according to the photodegradation and corona degradation theory of polyethylene. The results also showed that there was a certain similarity between photo aging and corona aging. IEEJ Trans 2010 DOI: 10.1002/tee.20600 相似文献
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Electrical properties of chemically modified polyethylenes 总被引:1,自引:0,他引:1
Suh K.S. Chang Ryong Lee Yutao Zhu Jangseob Lim 《Dielectrics and Electrical Insulation, IEEE Transactions on》1997,4(6):681-687
This report describes electrical properties such as space charge distribution, water treeing characteristics and ac breakdown strength in PE (polyethylene) modified by grafting and blending techniques. A control PE shows heterocharge. In AA (acrylic acid)-grafted PE (LDPE-g-AA), the heterocharge observed in PE decreases at low AA contents and homocharge is observed at high AA contents. In NBA (n-butyl acrylate)-grafted PE (LDPE-g-NBA), on the other hand, this heterocharge gets larger at all graft ratios to 0.12%. However, these components decrease the water tree length measured under specific conditions and increase ac breakdown strength. Details of the results are described and their origins are discussed. The results obtained with the LDPE-g-NBA are compared with those of PE/ethylene NBA copolymer blends 相似文献