The coupling effect of interfacial traps and molecular motion on the electrical breakdown in polyethylene nanocomposites

Min, Daomin; Cui, Haozhe; Wang, Weiwang; Wu, Qiang; Xing, Zhaoliang; Li, Shengtao

doi:10.1016/j.compscitech.2019.107873

Cited by 28 publications

(17 citation statements)

References 43 publications

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“…To implement the proposed method, we employed two main governing equations, based on the BCT and MCD models, respectively. The BCT model was used to analyze the space charge behavior as a function of electric field distribution within the insulator using electrons and holes as charge carriers [18], [21]- [23]. By fully coupling the BCT model and Poisson's equation, we were able to analyze the distortion in the electric field arising from the space charge distribution.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…Recently, the application of the BCT model to polymeric insulators has been analyzed in terms of various parameters, including the voltage ramp rate, temperature, thickness, and waveform of applied voltage [6], [10], [17]. The molecular chain displacement (MCD) model has also been suggested as a method for explaining the breakdown mechanism at the molecular chain scale [10], [18]- [20]. Until now, however, only a limited range of parameters have been considered, and owing to their nonlinear correlations, few of them have been evaluated.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Prediction of DC Breakdown Characteristics in LDPE With Current Profile as Critical Index

Kim

Lee

2020

IEEE Access

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Understanding the DC breakdown characteristics of polymeric insulators is essential for stable operation of high-capacity DC electrical equipment. To predict the breakdown characteristics of lowdensity polyethylene (LDPE), we propose a numerical methodology with a new critical index in which the internal current varying with temperature, thickness, and injection barrier height. To evaluate this currentbased index, we applied the fully coupled bipolar charge transport (BCT) and molecular chain displacement (MCD) models to analyze the influence of each variable on breakdown phenomena. The results of this analysis revealed that the amount of space charge accumulation within the insulator has a maximum value at approximately 50 ℃, which corresponds to the known morphological transition temperature of LDPE. The breakdown strength calculated using this numerical model was found to decrease with increasing temperature and thickness. Although injection barrier height at the electrode was found to be negatively correlated with breakdown strength, its effect was not as significant as that of the other variables. The breakdown strength values obtained using this numerical method were found to be in close agreement with values reported in the literature. Based on these results, we newly suggest the physical quantity to predict the breakdown strength, the current relaxation speed, which is the slope of the Boltzmann sigmoid function, as a positively correlated index. Finally, we determined that the breakdown phenomena are initiated when the amount of impact accumulated in the insulator changes discontinuously and analyzed the contribution of factors affecting the breakdown using the Pearson correlation coefficient and the Sobol sensitivity index.

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Section: Theoretical Backgroundmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical Prediction of DC Breakdown Characteristics in LDPE With Current Profile as Critical Index

Kim

Lee

2020

IEEE Access

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“…Dielectric constant (ε ) and dielectric loss (ε") test results of five samples at 40, 60, and 80 • C are shown in Figures 3 and 4, where the test frequency is from 10 −2 to 10 4 Hz, where α and δ relaxation processes occur at high and low frequencies, respectively. Frist, both the ε and ε" results show a remarkable relaxation peak above 10 Hz, which is α relaxation process, and the α relaxation is closely relevant to the displacement of molecular segments in the polymer [22,23]. Then, we can find that both ε and ε" spectrum have an upward process when the frequency continues to decline.…”

Section: Dielectric Constant and Dielectric Lossmentioning

confidence: 81%

“…The dielectric relaxation process δ involves hopping polarization [23]. Localized charges (ions or vacancies) hop among the localized states, leaving opposite polarity charges at different positions to form dipoles [22].…”

Section: Thermal Ion Polarization Behavioursmentioning

confidence: 99%

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Coupling Effect of Molecular Chain Displacement and Carrier Trap Characteristics on DC Breakdown of HDPE/LDPE Blend Insulation

Fan

Zhong

2020

Polymers

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This work focuses on the coupling effect of molecular chain displacement and trap characteristics on direct current (DC) breakdown properties of high density/low density polyethylene (HDPE/LDPE) blend insulation. Frequency domain spectroscopy (FDS) and isothermal discharge current (IDC) are used to characterize the dielectric relaxation and trap characteristics of HDPE/LDPE blends. A DC breakdown model is proposed to reveal the mechanisms of the molecular chain displacement and carrier trap on the DC breakdown strength. The dielectric relaxation α and δ present segmental motions and thermal ion polarization behaviours of HDPE/LDPE blends, respectively. α dielectric relaxation strength (Δεα) increases as the amount of HDPE increases from 0 to 5 wt%, and then declines with a further increase of HDPE content to 20 wt%. According to the velocity equation, the increase of Δεα will increase the molecular chain displacement, resulting in a larger free volume, which will provide electrons with larger free path λ to form hot electrons. A positive correlation exists between the activation energy of the dielectric relaxation process δ and trap density, and the increase of δ dielectric relaxation strength (Δεδ) will adversely affect the breakdown strength of the specimen. HDPE/LDPE blends with 15 wt% HDPE content have lower Δεα and lowest Δεδ, which decreases the mean free path λ of molecular chain and thermal ion polarization. At the same time, it has the highest deep trap density, thus increasing the probability of hot electrons being captured and improving the DC breakdown strength. It is concluded the breakdown of the dielectric is synergistically affected by the molecular chain displacement and carrier trap.

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High‐Temperature Polymer Dielectrics for Aerospace Electrical Equipment

Min,

Song,

Yang

et al. 2023

High Temperature Polymer Dielectrics

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The coupling effect of interfacial traps and molecular motion on the electrical breakdown in polyethylene nanocomposites

Cited by 28 publications

References 43 publications

Numerical Prediction of DC Breakdown Characteristics in LDPE With Current Profile as Critical Index

Numerical Prediction of DC Breakdown Characteristics in LDPE With Current Profile as Critical Index

Coupling Effect of Molecular Chain Displacement and Carrier Trap Characteristics on DC Breakdown of HDPE/LDPE Blend Insulation

High‐Temperature Polymer Dielectrics for Aerospace Electrical Equipment

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