scholarly journals Conductance Current and Space Charge Characteristics of SiO2/MMT/LDPE Micro-Nano Composites

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4119
Author(s):  
Hongtao Jiang ◽  
Xiaohong Zhang ◽  
Junguo Gao ◽  
Ning Guo
Keyword(s):  
Crystal Structure ◽  
Space Charge ◽  
Field Intensity ◽  
Nano Composites ◽  
Charge Accumulation ◽  
Inorganic Particles ◽  
Accumulation Curve ◽  
Space Charge Distribution ◽  
The Matrix ◽  
Sio2 Particles

Low-density polyethylene (LDPE) is one of the most comprehensive products used as insulation materials in power equipment. How to improve its dielectric properties by doping inorganic particles in LDPE has always been the focus of many researchers. In this paper, silica (SiO2) particles and montmorillonite (MMT) particles were added to LDPE, the order of adding particles was changed, and different micro-nano composites was made. The crystallization characteristics of composites were analyzed, the curves of the conductance current with the change of field intensity were analyzed, and the space charge distribution of each material were investigated. The results of crystallization show that the crystalline properties and crystallinity of the composites are higher than the matrix LDPE, the addition of SiO2 particles increases the composites’ crystallinity significantly, and the intercellular spacing of micro-nano composites is the smallest among all materials. The curve of conductance current versus electric field intensity shows that the tightness of the crystal structure can effectively hinder the movement of the molecular chain, inhibit carrier migration, while shortening the free travel of electrons, thereby reducing the electric conduction current of the material. The experimental results of the space charge accumulation curve further show that the compact crystal structure of the material is beneficial to the dissipation of space charge in the dielectric.

scholarly journals Composite Micro-Nanoarchitectonics of MMT-SiO2: Space Charge Characteristics under Tensile State

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4354
Author(s):  
Hongtao Jiang ◽  
Junguo Gao ◽  
Xiaohong Zhang ◽  
Ning Guo
Keyword(s):  
Crystal Structure ◽  
Composite Materials ◽  
Tensile Stress ◽  
Space Charge ◽  
Low Density Polyethylene ◽  
Nano Composites ◽  
Low Density ◽  
Charge Accumulation ◽  
Charge Mobility ◽  
Stretching Ratio

Low density polyethylene (LDPE) is a good insulating material which is widely used in cable materials due to its excellent insulation and processability. However, in the DC high voltage environment, pure polyethylene materials still face many problems, the most serious of which is space charge accumulation. The cable will inevitably be subjected to tensile stress during production, installation and operation. Therefore, it is of great significance to study the effect of stretching on the microstructure and space charge characteristics for polymers and their composites. In this paper, MMT/LDPE micro-composites, SiO2/LDPE nano-composites and MMT-SiO2/LDPE micro-nano-composites were prepared by melt blending. Mechanical stretching was carried out on pure LDPE materials and the above three kinds of composite materials. Each material was stretched according to four stretching ratios, which are 0%, 5%, 10% and 20%. The crystal morphology was observed by polarizing microscope (PLM), the crystallization perfection was tested by differential scanning calorimetry (DSC), and the space charge distribution inside each sample was measured by pulsed electro-acoustic (PEA) method. At the same time, the average charge density and apparent charge mobility for samples during depolarization were calculated and analyzed. The experimental results show that when the pure low density polyethylene sample is not stretched, its crystal structure is loose. Tensile stress can make the loose molecular chains align in LDPE and improve its crystalline structure, which is helpful to restrain the accumulation of space charge inside the sample. For MMT/LDPE, SiO2/LDPE and MMT-SiO2/LDPE composites, their internal crystal structure is compact. Stretching will destroy their original crystal structure at first, and then disorder molecular chains inside the three composite materials. With the increase of stretching ratio, the molecular chains begin to orient along the direction of force, the crystallization tends to be perfect gradually, and the space charge accumulation in samples also decreases. From the calculation results of apparent charge mobility for each sample, with the increase of stretching ratio, the trap depth and trap density inside samples firstly increased and then decreased.

scholarly journals The Effects of Nano Fillers on Space Charge Distribution in Cross-Linked Polyethylene

2017 ◽  
Vol 7 (6) ◽  
pp. 3147
Author(s):  
A. N. Ramani ◽  
A. M. Ariffin ◽  
Gobinath Vijian ◽  
Ahmad Basri Abd Ghani
Keyword(s):  
Space Charge ◽  
Charge Distribution ◽  
Room Temperature ◽  
Electrical Breakdown ◽  
Research Work ◽  
Field Enhancement ◽  
Insulation Material ◽  
Charge Accumulation ◽  
Space Charge Distribution ◽  
Local Electric Field Enhancement

The performance of polymeric insulation will be distorted by the accumulation of space charge. This will lead to local electric field enhancement within the insulation material that can cause degradation and electrical breakdown. The introduction of nanofillers in the insulation material is expected to reduce the space charge effect. However, there is a need to analyze potential nanofillers to determine the best option. Therefore, the objective of this research work is to examine two types of nanofillers for Cross-Linked Polyethylene (XLPE); Zinc Oxide (ZnO) and Acrylic (PA40). The effects of these nanofillers were measured using the Pulsed-Electro Acoustic (PEA) method. The development of space charge is observed at three different DC voltage levels in room temperature. The results show that hetero charge distribution is dominant in pure XLPE materials. The use of both nanofiller types have significant effect in decreasing the space charge accumulation. With nanofillers, the charge profile changed to homo-charge distribution, suppressing the space charge formation. Comparison<br />between both the nanofillers show that PA40 has better suppression performance than ZnO.

scholarly journals Effect of Semiconductive Layer on Space Charge Accumulation in XLPE

2020 ◽  
Vol 204 ◽  
pp. 02004
Author(s):  
Bai Huan ◽  
Guangmao Li ◽  
Gang Du ◽  
Jun Xiong ◽  
Wenxiong Mo
Keyword(s):  
Charge Density ◽  
Space Charge ◽  
High Voltage ◽  
Characteristic Parameter ◽  
Space Charge Density ◽  
Conductive Layer ◽  
Charge Accumulation ◽  
Space Charge Distribution ◽  
Long Time ◽  
Different Thickness

Long time DC pressure on high voltage cables will lead to the accumulation of space charge in XLPE cables, thus endangering cable insulation. In order to study the effect of the thickness of semiconducting layer on the space charge in XLPE, the space charge in 10kV and 220kV XLPE sample with different thickness of semiconducting layer was measured and compared based on PEA method. Firstly, the samples were pressurized to the specified voltage, then kept this voltage for 30 minutes, then depressurized to 0, and lastly maintained for 90 minutes. The variation of space charge distribution during the pressurized stage was analyzed with the space charge density as the characteristic parameter. The results show that the space charge near the anode and cathode is accumulated by the semi-conductive coating during the period of maintaining pressure; the thicker the semi-conductive layer is, the more obvious the accumulation of space charge is; the longer the time of maintaining pressure, the more space charge accumulates.

scholarly journals Dielectric and AC Breakdown Properties of SiO2/MMT/LDPE Micro–Nano Composites

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1235
Author(s):  
Hongtao Jiang ◽  
Xiaohong Zhang ◽  
Junguo Gao ◽  
Ning Guo
Keyword(s):  
Experimental Data ◽  
Field Strength ◽  
Dielectric Constants ◽  
Low Density Polyethylene ◽  
Breakdown Field ◽  
Nano Composites ◽  
Low Density ◽  
Inorganic Particles ◽  
The Matrix ◽  
Breakdown Field Strength

Low-density polyethylene (LDPE) is an important thermoplastic material which can be made into films, containers, wires, cables, etc. It is highly valued in the fields of packaging, medicine, and health, as well as cables. The method of improving the dielectric property of materials by blending LDPE with inorganic particles as filler has been paid much attention by researchers. In this paper, low-density polyethylene is used as the matrix, and montmorillonite (MMT) particles and silica (SiO2) particles are selected as micro and nano fillers, respectively. In changing the order of adding two kinds of particles, a total of five composite materials were prepared. The crystallization behavior and crystallinity of five kinds of composites were observed, the εr and tanδ changes of each material were investigated with frequency and temperature, and the power frequency (50 Hz) AC breakdown performance of materials were measured. The differential scanning calorimetry (DSC) and X-ray diffraction (XRD) results show that the crystallinity of the composites is higher than that of LDPE. Experimental data of dielectric frequency spectra show that the dielectric constants of micro–nano composites and composites with added MMT particles are lower than LDPE, the dielectric loss of composites can be improved by adding MMT particles. The experimental data of dielectric temperature spectra show that the permittivity of SiO2-MMT/LDPE is still at a low level under the condition of 20~100 °C. In terms of breakdown field strength, the SiO2/LDPE composite material increased by about 17% compared with the matrix LDPE, and the breakdown field strength of the materials SiO2-MMT/LDPE and MMT-SiO2/LDPE increased by about 6.8% and 4.6%, respectively.

Influence of Space Charge Accumulation by Pre-stress on Partial Discharge Inception Voltage

2020 ◽  
Vol 140 (5) ◽  
pp. 276-284
Author(s):  
Maimi Mima ◽  
Tokihiro Narita ◽  
Hiroaki Miyake ◽  
Yasuhiro Tanaka ◽  
Masahiro Kozako ◽  
...  
Keyword(s):  
Space Charge ◽  
Partial Discharge ◽  
Charge Accumulation ◽  
Inception Voltage

Space Charge Distribution Measurement in FEP Film Irradiated by Proton

2020 ◽  
Vol 140 (10) ◽  
pp. 504-505
Author(s):  
Kaisei Enoki ◽  
Ushio Chiba ◽  
Hiroaki Miyake ◽  
Yasuhiro Tanaka
Keyword(s):  
Space Charge ◽  
Charge Distribution ◽  
Distribution Measurement ◽  
Space Charge Distribution

Structural/Property Relationships for Optical Materials

1993 ◽  
Vol 329 ◽  
Author(s):  
Vivien D.
Keyword(s):  
Crystal Structure ◽  
Optical Properties ◽  
Electronic Structure ◽  
Chemical Composition ◽  
Field Strength ◽  
Optical Materials ◽  
Site Occupancy ◽  
Laser Materials ◽  
Crystal Field Strength ◽  
The Matrix

AbstractIn this paper the relationships between the crystal structure, chemical composition and electronic structure of laser materials, and their optical properties are discussed. A brief description is given of the different laser activators and of the influence of the matrix on laser characteristics in terms of crystal field strength, symmetry, covalency and phonon frequencies. The last part of the paper lays emphasis on the means to optimize the matrix-activator properties such as control of the oxidation state and site occupancy of the activator and influence of its concentration.

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