scholarly journals Carrier Transport and Molecular Displacement Modulated dc Electrical Breakdown of Polypropylene Nanocomposites

Polymers ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1207 ◽  
Author(s):  
Daomin Min ◽  
Chenyu Yan ◽  
Rui Mi ◽  
Chao Ma ◽  
Yin Huang ◽  
...  

Dielectric energy storage capacitors have advantages such as ultra-high power density, extremely fast charge and discharge speed, long service lifespan and are significant for pulsed power system, smart power grid, and power electronics. Polypropylene (PP) is one of the most widely used dielectric materials for dielectric energy storage capacitors. It is of interest to investigate how to improve its electrical breakdown strength by nanodoping and the influencing mechanism of nanodoping on the electrical breakdown properties of polymer nanocomposites. PP/Al2O3 nanocomposite dielectric materials with various weight fraction of nanoparticles are fabricated by melt-blending and hot-pressing methods. Thermally stimulated current, surface potential decay, and dc electrical breakdown experiments show that deep trap properties and associated molecular chain motion are changed by incorporating nanofillers into polymer matrix, resulting in the variations in conductivity and dc electrical breakdown field of nanocomposite dielectrics. Then, a charge transport and molecular displacement modulated electrical breakdown model is utilized to simulate the dc electrical breakdown behavior. It is found that isolated interfacial regions formed in nanocomposite dielectrics at relatively low loadings reduce the effective carrier mobility and strengthen the interaction between molecular chains, hindering the transport of charges and the displacement of molecular chains with occupied deep traps. Accordingly, the electrical breakdown strength is enhanced at relatively low loadings. Interfacial regions may overlap in nanocomposite dielectrics at relatively high loadings so that the effective carrier mobility decreases and the interaction between molecular chains may be weakened. Consequently, the molecular motion is accelerated by electric force, leading to the decrease in electrical breakdown strength. The experiments and simulations reveals that the influence of nanodoping on dc electrical breakdown properties may origin from the changes in the charge transport and molecular displacement characteristics caused by interfacial regions in nanocomposite dielectrics.

2013 ◽  
Vol 03 (01) ◽  
pp. 1330001 ◽  
Author(s):  
Xihong Hao

With the fast development of the power electronics, dielectric materials with high energy-storage density, low loss, and good temperature stability are eagerly desired for the potential application in advanced pulsed capacitors. Based on the physical principals, the materials with higher saturated polarization, smaller remnant polarization, and higher electrical breakdown field are the most promising candidates. According to this rule, so far, four kinds of materials, namely antiferroelectrics, dielectric glass-ceramics, relaxor ferroelectric and polymer-based ferroelectrics are thought to be more likely used in next-generation pulsed capacitors, and have been widely studied. Thus, this review serves to give an overall summary on the state-of-the-art progress on electric energy-storage performance in these materials. Moreover, some general future prospects are also provided from the existed theoretical and experimental results in this work, in order to propel their application in practice.


Polymers ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1012 ◽  
Author(s):  
Daomin Min ◽  
Yuwei Li ◽  
Chenyu Yan ◽  
Dongri Xie ◽  
Shengtao Li ◽  
...  

Polyimide has excellent electrical, thermal, and mechanical properties and is widely used as a dielectric material in electrical equipment and electronic devices. However, the influencing mechanism of sample thickness on electrical breakdown of polyimide has not been very clear until now. The direct current (DC) electrical breakdown properties of polyimide as a function of thickness were investigated by experiments and simulations of space charge modulated electrical breakdown (SCEB) model and charge transport and molecular displacement modulated (CTMD) model. The experimental results show that the electrical breakdown field decreases with an increase in the sample thickness in the form of an inverse power function, and the inverse power index is 0.324. Trap properties and carrier mobility were also measured for the simulations. Both the simulation results obtained by the SCEB model and the CTMD model have the inverse power forms of breakdown field as a function of thickness with the power indexes of 0.030 and 0.339. The outputs of the CTMD model were closer to the experiments. This indicates that the displacement of a molecular chain with occupied deep traps enlarging the free volume might be a main factor causing the DC electrical breakdown field of polyimide varying with sample thickness.


2021 ◽  
Vol 130 (14) ◽  
pp. 144101
Author(s):  
Jeffrey X. Zheng ◽  
Dixiong Wang ◽  
Pariasadat Musavigharavi ◽  
Merrilyn Mercy Adzo Fiagbenu ◽  
Deep Jariwala ◽  
...  

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3562 ◽  
Author(s):  
Chang Liu ◽  
Yiwen Xu ◽  
Daoguang Bi ◽  
Bing Luo ◽  
Fuzeng Zhang ◽  
...  

AlN nanoparticles were added into commercial high-temperature-vulcanized silicon rubber composites, which were designed for high-voltage outdoor insulator applications. The composites were systematically studied with respect to their mechanical, electrical, and thermal properties. The thermal conductivity was found to increase greatly (>100%) even at low fractions of the AlN fillers. The electrical breakdown strength of the composites was not considerably affected by the AlN filler, while the dielectric constants and dielectric loss were found to be increased with AlN filler ratios. At higher doping levels above 5 wt% (~2.5 vol%), electrical tracking performance was improved. The AlN filler increased the tensile strength as well as the hardness of the composites, and decreased their flexibility. The hydrophobic properties of the composites were also studied through the measurements of temperature-dependent contact angle. It was shown that at a doping level of 1 wt%, a maximum contact angle was observed around 108°. Theoretical models were used to explain and understand the measurement results. Our results show that the AlN nanofillers are helpful in improving the overall performances of silicon rubber composite insulators.


1989 ◽  
Vol 162 ◽  
Author(s):  
G. A. J. Amaratunga ◽  
W. I. Milne ◽  
A. Putnis ◽  
K. K. Chan ◽  
K. J. Clay ◽  
...  

ABSTRACTThin C films deposited from a CH4/Ar plasma on Si substrates kept at 20C are shown to be semiconducting. The semiconducting properties are associated with the poly-crystalline diamond grains present within the films. Diode type I-V characteristics observed from AVC/Si verticle structures are explained by the action of a C-Si heterojunction. A band gap of 2eV, a resistivity of 106Ω.cm and an electrical breakdown strength of 5.106 V/cm are estimated for the C.


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