纳米SiO_2/低密度聚乙烯复合材料的陷阱特性与电击穿机制
|
摘要
以低密度聚乙烯(LDPE)为聚合物基体,通过熔融共混的方式填充不同粒径的纳米SiO_2无机颗粒,制备纳米SiO_2/LDPE复合材料,研究提高聚乙烯电绝缘性能的纳米改性方法和机制。利用SEM表征纳米SiO_2在LDPE基体中的微观形态和分散程度,采用DSC和偏光显微镜(PLM)分析纳米SiO_2对LDPE基体结晶度和结晶形态的影响,通过热刺激电流法(TSC)分析纳米SiO_2/LDPE复合材料的陷阱密度和陷阱能级,并结合电击穿的Weibull分布研究纳米复合材料的击穿机制。研究结果表明:纳米SiO_2填充可以改变复合材料结晶度,进而增加LDPE基体本征结构缺陷和陷阱密度,同时填充纳米SiO_2颗粒可引入比LDPE基体本征陷阱更深的陷阱能级,纳米SiO_2填充颗粒引入的陷阱能级深度随着复合材料结晶度的增加而先增大后减小,填充浓度3wt%时可最有效地通过俘获载流子而抑制电击穿过程,纳米SiO_2/LDPE复合材料的击穿场强达到最高值。与60nm SiO_2颗粒相比,30nm SiO_2填充颗粒具有更高的比表面积,界面电极化导致更高的介电常数,更高密度的纳米界面深陷阱态对于提高电击穿场强更有效。当填充浓度为5wt%时,纳米颗粒的团聚作用导致纳米复合材料的击穿强度降低。基于电双层理论提出了电子捕捉模型和界面结构模型,合理阐释了纳米SiO_2/LDPE复合材料的微观陷阱特性及宏观电击穿机制。
The silicon dioxide/low density polyethylene(SiO_2/LDPE)nanocomposites were developed by filling SiO_2 nanoparticles into LDPE matrix with melt-blending preparing method to investigate nano-modification method and correlated mechanism for insulation performance improvement of LDPE.The micro-morphology and dispersivity of SiO_2 nanofillers composite in LDPE matrix were characterized by scanning electron microscopy(SEM).The differential scanning calorimetry(DSC)and polarizing microscope(PLM)were employed to testify the effects of SiO_2 nanofillers on the crystallinity and crystal morphology of LDPE matrix.The trap energy level and density were tested by thermal stimulated current(TSC),combining the Weibull statistics of electric breakdown strength to investigate insulation breakdown performance and attributed mechanism.The nano-SiO_2 filling rate can change the crystallinity of composites,while the change will increase the intrinsic structural defects and trap density of LDPE matrix.At the same time,filling nano-SiO_2 particles can introduce deeper trap levels than the intrinsic traps of LDPE matrix.Therefore,the most efficient inhibition to electric breakdown process by trapping charge carriers with largest energy,and thus the maximum breakdown strength are obtained for 3 wt%filling rate of SiO_2/LDPE nanocomposites.In comparison with 60 nm SiO_2 nanoparticles,the 30 nm SiO_2 nanoparticles with larger specific surface area filled into LDPE render higher dielectric permittivity from SiO_2-LDPE interface polarization,indicating the more efficient enhancement for electric breakdown strength by higher-density deep traps at larger-area nano-interfaces.Based on dielectric double-layer theory,the reliable models of electron capture and interface structure were put forward so as to reasonably represent the microscopic trap characteristics and macroscopic electric breakdown mechanism of SiO_2/LDPE nanocomposites.
The silicon dioxide/low density polyethylene(SiO_2/LDPE)nanocomposites were developed by filling SiO_2 nanoparticles into LDPE matrix with melt-blending preparing method to investigate nano-modification method and correlated mechanism for insulation performance improvement of LDPE.The micro-morphology and dispersivity of SiO_2 nanofillers composite in LDPE matrix were characterized by scanning electron microscopy(SEM).The differential scanning calorimetry(DSC)and polarizing microscope(PLM)were employed to testify the effects of SiO_2 nanofillers on the crystallinity and crystal morphology of LDPE matrix.The trap energy level and density were tested by thermal stimulated current(TSC),combining the Weibull statistics of electric breakdown strength to investigate insulation breakdown performance and attributed mechanism.The nano-SiO_2 filling rate can change the crystallinity of composites,while the change will increase the intrinsic structural defects and trap density of LDPE matrix.At the same time,filling nano-SiO_2 particles can introduce deeper trap levels than the intrinsic traps of LDPE matrix.Therefore,the most efficient inhibition to electric breakdown process by trapping charge carriers with largest energy,and thus the maximum breakdown strength are obtained for 3 wt%filling rate of SiO_2/LDPE nanocomposites.In comparison with 60 nm SiO_2 nanoparticles,the 30 nm SiO_2 nanoparticles with larger specific surface area filled into LDPE render higher dielectric permittivity from SiO_2-LDPE interface polarization,indicating the more efficient enhancement for electric breakdown strength by higher-density deep traps at larger-area nano-interfaces.Based on dielectric double-layer theory,the reliable models of electron capture and interface structure were put forward so as to reasonably represent the microscopic trap characteristics and macroscopic electric breakdown mechanism of SiO_2/LDPE nanocomposites.
引文
[1]樊玮,张超,刘天西.石墨烯/聚合物复合材料的研究进展[J].复合材料学报,2013,30(1):14-21.FAN Wei,ZHANG Chao,LIU Tianxi,et al.Recent progress in graphene/polymer composites[J].Acta Materiae Compositae Sinica,2013,30(1):14-21(in Chinese).
[2]田付强,杨春,何丽娟,等.聚合物/无机纳米复合电介质介电性能及其机理最新研究进展[J].电工技术学报,2011,26(3):1-12.TIAN Fuqiang,YANG Chun,HE Lijuan,et al.Recent research advancement in dielectric properties and the corresponding mechanism of polymer/inorganic nanocomposite[J].Transaction of China Electrotechnical Society,2011,26(3):1-12(in Chinese).
[3]罗杨,吴广宁,彭佳,等.聚合物纳米复合电介质的界面性能研究进展[J].高电压技术,2012,38(9):2455-2464.LUO Yang,WU Guangning,PENG Jia,et al.Research Progress on Interface Properties of Polymer Nanodielectrics[J].High Voltage Engineering,2012,38(9):2455-2464(in Chinese).
[4]IEDA M.Dielectric breakdown process of polymers[J].Electrical Insulation IEEE Transactions,1980,EI-15(3):206-224.
[5]DU B X,LIU Y,LIU H J.A study on breakdown phenomenon identification of polymer films[C]//Indianapolis:Proceeding of Electrical Insulation Conference and Electrical Manufacturing Expo,IEEE,2005:178-181.
[6]HONG N P,IM P G,KIM D J,et al.The electrical breakdown properties of low density polyethylene film due to morphological change[C]//Millbrae:Proceeding of Electrical Insulation and Dielectric Phenomena.IEEE,1996:692-696.
[7]WANG W W,LI S T,TANG F,et al.Characteristics on breakdown performance of polyethylene/silica dioxide nanocomposites[J].Electrical Insulation and Dielectric Phenomena,2012,48(11):521-524.
[8]兰莉,吴建东,纪哲强,等.纳米SiO2/低密度聚乙烯复合介质的击穿特性[J].中国电机工程学报,2012,32(13):138-143.LAN Li,WU Jiandong,JI Zheqiang,et al.Breakdown properties of nano-SiO2/LDPE composite[J].Proceedings of the CSEE,2012,32(13):138-143(in Chinese).
[9]LAU K Y,VAUGHAN A S,CHEN G,et al.On the space charge and DC breakdown behavior of polyethylene/silica nanocomposites[J].IEEE Transactions on Dielectrics and Electrical Insulation,2014,21(1):340-351.
[10]VEENA M G,RENUKAPPA N M,SHIVAKUMAR K N,et al.Study of interface behavior on dielectric properties of epoxy-silica nanocomposites[C]//Bangalore:Proceeding of International Conference on the Properties and Applications of Dielectric Materials.IEEE,2012:1-4.
[11]ROY M,NELSON J K,MACCRONE R K,et al.Polymer nanocomposite dielectrics-the role of the interface[J].IEEE Transactions on Dielectrics and Electrical Insulation,2005,12(4):629-643.
[12]LEWIS T J.Interfaces are the dominant feature of dielectrics at the nanometric level[J].IEEE Transactions on Dielectrics and Electrical Insulation,2004,11(5):739-753.
[13]TANAKA T,KOZAKO M,FUSE N,et al.Proposal of a multi-core model for polymer nanocomposite dielectrics[J].IEEE Transactions on Dielectrics and Electrical Insulation,2005,12(4):669-681.
[14]TANAKA T.Interpretation of several key phenomena peculiar to nano dielectrics in terms of a multi-core model[C]//Kansas:Proceeding of Electrical Insulation and Dielectric Phenomena[J].IEEE,2006:298-301.
[15]王金锋,郑晓泉,柳立为,等.LDPE结晶形态对水树枝老化特性的影响[J].高电压技术,2010,36(3):678-684.WANG Jinfeng,ZHENG Xiaoquan,LIU Liwei,et al.Influence of Crystalline Morphology on Water Treeing in LDPE[J].High Voltage Engineering,2010,36(3):678-684(in Chinese).
[16]盛淼,杜中杰,荣峻峰,等.DSC法研究原位聚合聚乙烯/凹凸棒石纳米复合材料的结晶行为[J].高分子材料科学与工程,2003,19(3):168-171.SHENG Miao,DU Zhongjie,RONG Junfeng,et al.Crystallization behabior of polyethylene/palygorskite nano-composite prepared via’in situ coordinated polymerization approach’tested by DSC[J].Polymermaterials Science and Engineering,2003,19(3):168-171(in Chinese).
[17]解云川,范晓东,孔杰,等.聚乙烯/蒙脱土复合材料的结晶行为[J].高分子材料科学与工程,2005,21(3):117-120.XIE Yunchuan,FAN Xiaodong,KONG Jie,et al.Study on the crystallization behaviors of polyethylene/MMT Hybrid System[J]. Polymermaterials Science and Engineering,2005,21(3):117-120(in Chinese).
[18]ALAPATI S,MELEDATH J T,KARMARKAR A.Effect of morphology on electrical treeing in low density polyethylene nanocomposites[J].Iet Science Measurement Technology,2014,8(2):60-68.
[19]程羽佳,张晓虹,周雪冬,等.冷却方式对MMT/LDPE介电性能的影响[J].无机材料学报,2015,30(12):1295-1302.CHENG Yujia,ZHANG Xiaohong,ZHOU Xuedong,et al.Effects of Cooling Methods on Dielectric Properties of MMT/LDPE[J].Journal of Inorganic Materials,2015,30(12):1295-1302(in Chinese).
[20]WANG W,MIN D,Li S.Understanding the conduction and breakdown properties of polyethylene nanodielectrics:effect of deep traps[J].IEEE Transactions on Dielectrics and Electrical Insulation,2016,23(1):564-572.
[21]王新生,屠德民.陷阱理论在聚丙烯电老化试验中的证实[J].西安交通大学学报,1993,27(6):43-48.WANG Xinsheng,TU Demin.Verification of The trap theory of polymer breakdown by electrical ageing in PP[J].Xi’an Jiaotong University Xuebao,1993,27(6):43-48(in Chinese).
[22]CHEN Y, WU J.Investigation on relationship between breakdown strength enhancement of composites and dielectric characteristics of nanoparticle[J].IEEE Transactions on Dielectrics and Electrical Insulation,2016,23(2):927-934.
[23]GAO M,ZHANG P,WANG F.Effect of percolation and interfacial characteristics on breakdown behavior of nano-Silica/Epoxy composites[C]//Ulaanbaatar:Proceeding of International Forum on Strategic Technology. IEEE, 2013:120-123.
[2]田付强,杨春,何丽娟,等.聚合物/无机纳米复合电介质介电性能及其机理最新研究进展[J].电工技术学报,2011,26(3):1-12.TIAN Fuqiang,YANG Chun,HE Lijuan,et al.Recent research advancement in dielectric properties and the corresponding mechanism of polymer/inorganic nanocomposite[J].Transaction of China Electrotechnical Society,2011,26(3):1-12(in Chinese).
[3]罗杨,吴广宁,彭佳,等.聚合物纳米复合电介质的界面性能研究进展[J].高电压技术,2012,38(9):2455-2464.LUO Yang,WU Guangning,PENG Jia,et al.Research Progress on Interface Properties of Polymer Nanodielectrics[J].High Voltage Engineering,2012,38(9):2455-2464(in Chinese).
[4]IEDA M.Dielectric breakdown process of polymers[J].Electrical Insulation IEEE Transactions,1980,EI-15(3):206-224.
[5]DU B X,LIU Y,LIU H J.A study on breakdown phenomenon identification of polymer films[C]//Indianapolis:Proceeding of Electrical Insulation Conference and Electrical Manufacturing Expo,IEEE,2005:178-181.
[6]HONG N P,IM P G,KIM D J,et al.The electrical breakdown properties of low density polyethylene film due to morphological change[C]//Millbrae:Proceeding of Electrical Insulation and Dielectric Phenomena.IEEE,1996:692-696.
[7]WANG W W,LI S T,TANG F,et al.Characteristics on breakdown performance of polyethylene/silica dioxide nanocomposites[J].Electrical Insulation and Dielectric Phenomena,2012,48(11):521-524.
[8]兰莉,吴建东,纪哲强,等.纳米SiO2/低密度聚乙烯复合介质的击穿特性[J].中国电机工程学报,2012,32(13):138-143.LAN Li,WU Jiandong,JI Zheqiang,et al.Breakdown properties of nano-SiO2/LDPE composite[J].Proceedings of the CSEE,2012,32(13):138-143(in Chinese).
[9]LAU K Y,VAUGHAN A S,CHEN G,et al.On the space charge and DC breakdown behavior of polyethylene/silica nanocomposites[J].IEEE Transactions on Dielectrics and Electrical Insulation,2014,21(1):340-351.
[10]VEENA M G,RENUKAPPA N M,SHIVAKUMAR K N,et al.Study of interface behavior on dielectric properties of epoxy-silica nanocomposites[C]//Bangalore:Proceeding of International Conference on the Properties and Applications of Dielectric Materials.IEEE,2012:1-4.
[11]ROY M,NELSON J K,MACCRONE R K,et al.Polymer nanocomposite dielectrics-the role of the interface[J].IEEE Transactions on Dielectrics and Electrical Insulation,2005,12(4):629-643.
[12]LEWIS T J.Interfaces are the dominant feature of dielectrics at the nanometric level[J].IEEE Transactions on Dielectrics and Electrical Insulation,2004,11(5):739-753.
[13]TANAKA T,KOZAKO M,FUSE N,et al.Proposal of a multi-core model for polymer nanocomposite dielectrics[J].IEEE Transactions on Dielectrics and Electrical Insulation,2005,12(4):669-681.
[14]TANAKA T.Interpretation of several key phenomena peculiar to nano dielectrics in terms of a multi-core model[C]//Kansas:Proceeding of Electrical Insulation and Dielectric Phenomena[J].IEEE,2006:298-301.
[15]王金锋,郑晓泉,柳立为,等.LDPE结晶形态对水树枝老化特性的影响[J].高电压技术,2010,36(3):678-684.WANG Jinfeng,ZHENG Xiaoquan,LIU Liwei,et al.Influence of Crystalline Morphology on Water Treeing in LDPE[J].High Voltage Engineering,2010,36(3):678-684(in Chinese).
[16]盛淼,杜中杰,荣峻峰,等.DSC法研究原位聚合聚乙烯/凹凸棒石纳米复合材料的结晶行为[J].高分子材料科学与工程,2003,19(3):168-171.SHENG Miao,DU Zhongjie,RONG Junfeng,et al.Crystallization behabior of polyethylene/palygorskite nano-composite prepared via’in situ coordinated polymerization approach’tested by DSC[J].Polymermaterials Science and Engineering,2003,19(3):168-171(in Chinese).
[17]解云川,范晓东,孔杰,等.聚乙烯/蒙脱土复合材料的结晶行为[J].高分子材料科学与工程,2005,21(3):117-120.XIE Yunchuan,FAN Xiaodong,KONG Jie,et al.Study on the crystallization behaviors of polyethylene/MMT Hybrid System[J]. Polymermaterials Science and Engineering,2005,21(3):117-120(in Chinese).
[18]ALAPATI S,MELEDATH J T,KARMARKAR A.Effect of morphology on electrical treeing in low density polyethylene nanocomposites[J].Iet Science Measurement Technology,2014,8(2):60-68.
[19]程羽佳,张晓虹,周雪冬,等.冷却方式对MMT/LDPE介电性能的影响[J].无机材料学报,2015,30(12):1295-1302.CHENG Yujia,ZHANG Xiaohong,ZHOU Xuedong,et al.Effects of Cooling Methods on Dielectric Properties of MMT/LDPE[J].Journal of Inorganic Materials,2015,30(12):1295-1302(in Chinese).
[20]WANG W,MIN D,Li S.Understanding the conduction and breakdown properties of polyethylene nanodielectrics:effect of deep traps[J].IEEE Transactions on Dielectrics and Electrical Insulation,2016,23(1):564-572.
[21]王新生,屠德民.陷阱理论在聚丙烯电老化试验中的证实[J].西安交通大学学报,1993,27(6):43-48.WANG Xinsheng,TU Demin.Verification of The trap theory of polymer breakdown by electrical ageing in PP[J].Xi’an Jiaotong University Xuebao,1993,27(6):43-48(in Chinese).
[22]CHEN Y, WU J.Investigation on relationship between breakdown strength enhancement of composites and dielectric characteristics of nanoparticle[J].IEEE Transactions on Dielectrics and Electrical Insulation,2016,23(2):927-934.
[23]GAO M,ZHANG P,WANG F.Effect of percolation and interfacial characteristics on breakdown behavior of nano-Silica/Epoxy composites[C]//Ulaanbaatar:Proceeding of International Forum on Strategic Technology. IEEE, 2013:120-123.