scholarly journals Effect of Particles Size on Dielectric Properties of Nano-ZnO/LDPE Composites

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 5 ◽  
Author(s):  
YuJia Cheng ◽  
Liyang Bai ◽  
Guang Yu ◽  
Xiaohong Zhang
Keyword(s):  
Field Strength ◽  
Crystal Habit ◽  
Experimental Result ◽  
Breakdown Field ◽  
Specimen Thickness ◽  
Scanning Calorimetry ◽  
Nano Zno ◽  
Zno Particles ◽  
Ldpe Composites ◽  
Breakdown Field Strength

The melt blending was used to prepare 3 wt% ZnO/low density polyethylene (ZnO/LDPE) nanocomposites in this article. The effect of different inorganic ZnO particles doping on the dielectrical property and crystal habit of LDPE matrix was explored. The nanoparticles size was 9 nm, 30 nm, 100 nm, and 200 nm respectively. Scanning electron microscope (SEM) was used to characterize ZnO nanoparticles whereas differential scanning calorimetry (DSC) was used to make thermal characterization of the samples. Besides, the AC (alternating current), DC (direct current breakdown characteristics and electrical conductivity of the nanocomposites was studied in this article. The experimental results showed that nano-ZnO/LDPE composites had the advantages such as small crystal size, high crystallization rate and crystallinity owing to nano-ZnO particles doping, when doping nano-ZnO particles size was 30 nm, the ZnO/LDPE nanocomposite crystallinity crest value 39.77% appeared. At the mean time, the DC and AC breakdown field strength values of composites were 138.0 kV/mm and 340.4 kV/mm respectively. They were the maximal values which improved 8.24% and 13.85% than LDPE. The AC breakdown field strength of samples decreased with specimen thickness increase. The DC breakdown field strength of LDPE and ZnO/LDPE composites were greater than AC breakdown field strength. From the conductivity experimental result it could be seen that when the experimental temperature and electric field intensity rose, the current density and conductivity of ZnO/LDPE composites increased with the enlargement of ZnO particles size. But the values were less than which of LDPE.

scholarly journals The Research of Conductivity and Dielectric Properties of ZnO/LDPE Composites with Different Particles Size

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4136 ◽  
Author(s):  
Yujia Cheng ◽  
Guang Yu ◽  
Boyang Yu ◽  
Xiaohong Zhang
Keyword(s):  
Dielectric Constant ◽  
Field Strength ◽  
Interfacial Polarization ◽  
Breakdown Field ◽  
Test Results ◽  
Nano Zno ◽  
Inorganic Particles ◽  
Zno Particles ◽  
Ldpe Composites ◽  
Breakdown Field Strength

Nanocomposites exhibit a high dielectric strength, whereas microcomposites exhibit a high thermal conductivity. In this study, good insulating materials were developed on the basis of the synergetic effect of micro- and nanoparticles, which were used as inorganic fillers. With a double-melting blend, nano-ZnO/low density polyethylene (LDPE), micro-ZnO/LDPE, and micro-nano-ZnO/LDPE composites were prepared, according to the scanning electron microscope test, polarization microscope test, conductivity test, breakdown test, and dielectric spectrum test, the dielectric property of micro-nano-ZnO/LDPE was explored. The SEM test results showed that by adding a suitable proportion of ZnO particles, the inorganic particles could disperse uniformly without reuniting. The PLM test results showed that the micro- and nano-ZnO particles adding decreased the crystal size. The arrangement was regular and tight. The macroscopic results showed that the mass fraction of nanoparticles and microparticles were 3% and 2%, the samples conductivity was the lowest. The breakdown field strength of the nanocomposites increased. The breakdown field strength of nanocomposites with 1%, 3%, and 5% nanoparticle contents were 5%, 15%, and 10% higher than that of pure LDPE. The addition of inorganic particles resulted in new polarization modes: Ionic displacement polarization and interfacial polarization. The ZnO/LDPE composites exhibited a higher dielectric constant and dielectric loss factor than pure LDPE. However, with the increasing frequency, it took considerable time to attain interfacial polarization in the nanocomposite and micro-nanocomposite, thus decreasing the dielectric constant.

scholarly journals Effect of Different Size ZnO Particle Doping on Dielectric Properties of Polyethylene Composites

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Yujia Cheng ◽  
Guang Yu ◽  
Zhuohua Duan
Keyword(s):  
Particle Size ◽  
Field Strength ◽  
Experimental Results ◽  
Dominant Factor ◽  
Breakdown Field ◽  
Inorganic Filler ◽  
Nano Zno ◽  
Zno Particles ◽  
The Matrix ◽  
Breakdown Field Strength

In this article, low density polyethylene was used as a matrix polymer. The ZnO particles with diameters of 30 nm and 1 μm were used as inorganic filler. The nano-ZnO particles after surface modification would disperse in the matrix uniformly. The nano-, micro-, and micro-/nano-ZnO/LDPE were prepared by melt blending. During the experiment, the microstructures of different composites were characterized and discussed by SEM and DSC. Besides, the micro- and nano-ZnO/LDPE underwent a breakdown test, conductance test, and dielectric spectrum test. The microscopic experimental results showed that the ZnO particles dispersed uniformly in the LDPE matrix. The crystallinity of composites was higher than that of pure LDPE. Among them, the maximum crystallinity was 39.77% when the nano-ZnO particle size was 30 nm. It was 16.1% higher than pure LDPE. The macroscopic experimental results showed that the effect of micro- and nano-ZnO particle doping on breakdown properties of polymers was different. Among them, the breakdown field strength of nano-ZnO/LDPE was the highest at 138.0 kV/mm, which was 8.24% higher than that of pure LDPE. The micro-/nano-ZnO/LDPE took second place, which was still higher than pure LDPE. As the thickness of samples increased, the thermal breakdown was the dominant factor in the breakdown test. The AC breakdown field strength of all composites tended to decrease, and the reduction of micro-ZnO/LDPE was lower than that of nano-ZnO/LDPE. Besides, the dispersion of the breakdown became better. Moreover, the micro- and nano-ZnO particle doping could improve the conductivity characteristic of polymer effectively. The dielectric constant and dielectric loss of composites increased with the increase of the particle size.

scholarly journals The Dielectric Properties Improvement of Cable Insulation Layer by Different Morphology Nanoparticles Doping into LDPE

Coatings ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 204 ◽  
Author(s):  
Guang Yu ◽  
Yujia Cheng ◽  
Xiaohong Zhang
Keyword(s):  
Dielectric Properties ◽  
Space Charge ◽  
Crystallization Rate ◽  
Crystal Habit ◽  
Breakdown Field ◽  
Interface Traps ◽  
Insulation Layer ◽  
Nano Zno ◽  
Cable Insulation ◽  
Zno Particles

Low density polyethylene (LDPE) doped with inorganic nano-MMT and nano-ZnO particles improved the dielectric properties of the cable insulation layer. In this article, nano-MMT/LDPE and nano-ZnO/LDPE composites were prepared by polymer intercalation and melt blending, respectively. The octadecyl quaternary ammonium salt and silane coupling agent were applied for surface modification in nano-MMT and nano-ZnO particles, and this then improved the compatibility of nanoparticles and polymeric matrix. These samples were characterized by FTIR, PLM, DSC and TSC, from which the effect of nanoparticles doping on polymer crystal habit and interface traps would be explored. In these experiments, the AC breakdown characteristics and space charge characteristic of different composites were studied. The experimental results showed that the interface bonding of nanoparticles and polymer was improved by coupling agents modifying. The dispersion of nanoparticles in matrix was better. When the mass fraction of nanoparticles doping was 3 wt.%, the crystallization rate and crystallinity of composites increased, and the crystalline structure was more complete. Besides, the amorphous regions in material decreased and the conducting channel was circuitous. At this time, the breakdown field strength of nano-MMT/LDPE and nano-ZnO/LDPE increased by 10.3% and 11.1%, compared to that of pure LDPE, respectively. Furthermore, the density and depth of interface traps in polymer increased with nanoparticles doping. Nano-MMT and nano-ZnO could both restrain the space charge accumulation, and the inhibiting effect of nano-ZnO was more visible.

scholarly journals Effects of Inorganic ZnO Particle Doping on Crystalline Polymer Morphology and Space Charge Behavior

Coatings ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 932
Author(s):  
Guang Yu ◽  
Yujia Cheng
Keyword(s):  
Space Charge ◽  
Short Circuit ◽  
Matrix Material ◽  
Breakdown Field ◽  
Polyethylene Matrix ◽  
Nano Zno ◽  
Zno Particles ◽  
The Matrix ◽  
Ldpe Composites ◽  
Field Strengths

This study further investigated the synergistic effect of micro- and nanofiller doping on matrix material space charges and breakdown characteristics. Accordingly, low-density polyethylene (LDPE) was used as the matrix material, and spherical ZnO particles with sizes of 30 nm and 1 µm were used as additives. Micro-ZnO/LDPE, nano-ZnO/LDPE, and micro-nano-ZnO/LDPE composites were prepared through melt blending. The crystalline morphologies of the composites were observed via polarized light microscopy. The composite crystallinity and melting peak temperature were measured via differential scanning calorimetry, and the micro- and nanoparticle dispersions in the matrix were observed via scanning electron microscopy. The test results showed that the particles were uniformly dispersed in the polyethylene matrix. The filler acted as a heterogeneous nucleation agent in the matrix. The crystal size decreased, thereby increasing the crystal quantity. The doping of inorganic ZnO particles improved the composite crystallinity. The ZnO/LDPE composites were subjected to DC breakdown, space charge, and dielectric spectrum tests. When the crystal arrangement of the sample was loose and its size was large, the breakdown process developed along a shorter path, and the field strength of the composite breakdown decreased. The order of AC and DC breakdown field strengths of the samples was as follows: micro-ZnO/LDPE < pure LDPE < micro-nano-ZnO/LDPE < nano-ZnO/LDPE. The DC and AC breakdown field strengths of the micro- and nano-ZnO/LDPE were 4.7% and 3.2% higher than those of the pure LDPE, respectively. Moreover, the DC and AC breakdown field strengths of the nano-ZnO/LDPE were 11.02% and 15.8% higher than those of the pure LDPE, respectively. The doping of inorganic ZnO particles restrained the space charge accumulation, and the residual charges decreased after short-circuit treatment. The dielectric constant of all nanocomposites was lower than that of LDPE, and the dielectric loss of all composites was higher than that of LDPE.

scholarly journals Effect of Acetylated SEBS/PP for Potential HVDC Cable Insulation

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1596
Author(s):  
Peng Zhang ◽  
Yongqi Zhang ◽  
Xuan Wang ◽  
Jiaming Yang ◽  
Wenbin Han
Keyword(s):  
Mechanical Properties ◽  
Field Strength ◽  
Thermoplastic Elastomer ◽  
High Energy ◽  
Thermoplastic Elastomers ◽  
Electrical Strength ◽  
Voltage Stabilizer ◽  
Breakdown Field ◽  
Cable Insulation ◽  
Breakdown Field Strength

Blending thermoplastic elastomers into polypropylene (PP) can make it have great potential for high-voltage direct current (HVDC) cable insulation by improving its toughness. However, when a large amount of thermoplastic elastomer is blended, the electrical strength of PP will be decreased consequently, which cannot meet the electrical requirements of HVDC cables. To solve this problem, in this paper, the inherent structure of thermoplastic elastomer SEBS was used to construct acetophenone structural units on its benzene ring through Friedel–Crafts acylation, making it a voltage stabilizer that can enhance the electrical strength of the polymer. The DC electrical insulation properties and mechanical properties of acetylated SEBS (Ac-SEBS)/PP were investigated in this paper. The results showed that by doping 30% Ac-SEBS into PP, the acetophenone structural unit on Ac-SEBS remarkably increased the DC breakdown field strength of SEBS/PP by absorbing high-energy electrons. When the degree of acetylation reached 4.6%, the DC breakdown field strength of Ac-SEBS/ PP increased by 22.4% and was a little higher than that of PP. Ac-SEBS, with high electron affinity, is also able to reduce carrier mobility through electron capture, resulting in lower conductivity currents in SEBS/PP and suppressing space charge accumulation to a certain extent, which enhances the insulation properties. Besides, the highly flexible Ac-SEBS can maintain the toughening effect of SEBS, resulting in a remarkable increase in the tensile strength and elongation at the break of PP. Therefore, Ac-SEBS/PP blends possess excellent insulation properties and mechanical properties simultaneously, which are promising as insulation materials for HVDC cables.

scholarly journals Space Charge Characteristics and Electrical Properties of Micro-Nano ZnO/LDPE Composites

Crystals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 481
Author(s):  
Jun-Guo Gao ◽  
Xia Li ◽  
Wen-Hua Yang ◽  
Xiao-Hong Zhang
Keyword(s):  
Electrical Properties ◽  
Space Charge ◽  
Synergistic Effects ◽  
Nano Particles ◽  
Breakdown Field ◽  
Nano Composite ◽  
Nano Zno ◽  
Additive Particles ◽  
Ldpe Composites ◽  
Short Connection

The synergistic effects of zinc oxide (ZnO) Micro/Nano particles simultaneously filled in low-density polyethylene (LDPE) on the space charge characteristics and electrical properties has been investigated by melt blending micro-scale and nanoscale ZnO additive particles into LDPE matrix to prepare Micro-ZnO, Nano-ZnO, and Micro-Nano ZnO/LDPE composites. The morphological structures of composite samples are characterized by Polarizing Light Microscopy (PLM), and the space charge accumulations and insulation performances are correlated in the analyses with Pulse Electronic Acoustic (PEA), DC breakdown field strength, and conductance tests. It is indicated that both the micro and nano ZnO fillers can introduce plenty of heterogeneous nuclei into the LDPE matrix so as to impede the LDPE spherocrystal growth and regularize the crystalline grains in neatly-arranged morphology. By filling microparticles together with nanoparticles of ZnO additives, the space charge accumulations are significantly inhibited under an applied DC voltage and the minimum initial residual charges with the slowest charge decaying rate have been achieved after an electrode short connection. While the micro-nano ZnO/LDPE composites acquire the lowest conductivity, the breakdown strengths of the ZnO/LDPE nanocomposite and micro-nano composite are, respectively, 13.7% and 3.4% higher than that of the neat LDPE material.

scholarly journals Study on the Structure and Dielectric Properties of Zeolite/LDPE Nanocomposite under Thermal Aging

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2108
Author(s):  
Bai Han ◽  
Chuqi Yin ◽  
Jiaxin Chang ◽  
Yu Pang ◽  
Penghao Lv ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Aging Time ◽  
Thermal Aging ◽  
Aging Treatment ◽  
Dielectric Strength ◽  
Breakdown Field ◽  
Scanning Calorimetry ◽  
Aging Resistance ◽  
The Stability ◽  
Breakdown Field Strength

Nanodoping is an effective way to improve the dielectric properties and the aging resistance of polyethylene. Nano-zeolite has a nano-level porous structure and larger specific surface area than ordinary nano-inorganic oxide, which can be used to improve dielectric properties of low-density polyethylene (LDPE) nanocomposite. The zeolite/LDPE nanocomposites were prepared and subjected to thermal aging treatment to obtain samples with different aging time. Using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and the differential scanning calorimetry (DSC) test to study the microscopic and structure characteristics, it was found that nano-zeolite doping can effectively reduce the thermal aging damage to the internal structure of the nanocomposite; carbonyl and hydroxyl decreased significantly during the thermal aging time, and the crystallinity effectively improved. Nano-zeolite doping significantly improved the morphology and strengthened the aging resistance of the nanocomposite. In the dielectric strength test, it was found that nanodoping can effectively improve the direct current (DC) and alternating current (AC) breakdown field strength and the stability after the thermal aging. The dielectric constant of nanocomposite can be reduced, and the dielectric loss had no obvious change during the aging process. Moreover, the zeolite/LDPE nanocomposite with the doping concentration of 1 wt % had the best performance, for the nano-zeolite was better dispersed.

Electrical Properties of a TiO2-SrO Varistor System

2014 ◽  
Vol 975 ◽  
pp. 168-172
Author(s):  
Tiago Delbrücke ◽  
Igor Schmidt ◽  
Sergio Cava ◽  
Vânia Caldas Sousa
Keyword(s):  
Titanium Dioxide ◽  
Electrical Properties ◽  
Field Strength ◽  
Leakage Current ◽  
Low Voltage ◽  
Nonlinear Coefficient ◽  
Breakdown Field ◽  
Strontium Oxide ◽  
Breakdown Field Strength

The addition of different dopants affects the densification and electrical properties of TiO2 based varistor ceramics. The nonlinear current (I) and voltage (V) characteristics of titanium dioxide are examined when doped with small quantities (0.5-2 at.%) of strontium oxide. This paper discusses the electrical properties of such an SrO doped TiO2 system, and demonstrates that some combinations produce electrical properties suitable for use as low voltage varistors. The high value of the nonlinear coefficient (α) (6.6), the breakdown field strength (Eb) (328 V/cm) and the leakage current (Ir) (0.22 mA/cm2) obtained in a system newly doped with SrO, are all adequate properties for application in low voltage varistors.

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