scholarly journals Mechanical and Dielectric Strength of Laminated Epoxy Dielectric Graded Materials

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 622
Author(s):  
Chuang Wang ◽  
Qing Sun ◽  
Lang Zhao ◽  
Jing Jia ◽  
Lixiao Yao ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Breakdown Strength ◽  
Dielectric Material ◽  
Dielectric Strength ◽  
Structural Motif ◽  
Cross Linking ◽  
Graded Materials ◽  
Interfacial Structures ◽  
Graded Material ◽  
Laminated Material

Laminated epoxy dielectric graded material is a commonly used insulating material with broad application prospects in power equipment. The interlaminar interfaces of laminated epoxy dielectric material between different layers form during its lamination process, and these interfaces are the crucial characteristic structures determining the mechanical and dielectric properties of laminated materials. Therefore, in order to gain a thorough understanding of physic properties behind a certain structural motif, it is necessary to study how these interfacial structures influence the mechanical and dielectric performances of graded materials. In this study, double-layered epoxy resin samples with an interlaminar interface are prepared to study their mechanical and dielectric strength. More importantly, the formation mechanism of the interface, as well as its influence on the mechanical and dielectric strength of this laminated material, is discussed. We found that a cross-linking reaction may take place between epoxy resins at the interlaminar interface, and the degree of cross-linking at the interface should be less than that in the bulk. The mechanical strength of the interlaminar interface is weaker than that of the bulk, and it is reduced by less than 40%. Moreover, the interlaminar interface is inclined to trap carriers, which improves the breakdown strength and arc ablation resistance of the laminated material. Our study of interlaminar interface properties could help in designing epoxy dielectric graded materials with better mechanical and dielectric properties.

scholarly journals Use of Grafted Voltage Stabilizer to Enhance Dielectric Strength of Cross-Linked Polyethylene

Polymers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 176 ◽  
Author(s):  
Wei Dong ◽  
Xuan Wang ◽  
Bo Tian ◽  
Yuguang Liu ◽  
Zaixing Jiang ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Breakdown Strength ◽  
Dielectric Strength ◽  
Voltage Stabilizer ◽  
Cross Linking ◽  
Practical Application ◽  
Electrical Tree ◽  
Research Goal ◽  
The Stability ◽  
New Research

Aromatic voltage stabilizers can improve the dielectric properties of cross-linked polyethylene (XLPE); however, their poor compatibility with XLPE hinders their practical application. Improving the compatibility of aromatic voltage stabilizers with XLPE has, therefore, become a new research goal. Herein 1-(4-vinyloxy)phenylethenone (VPE) was prepared and characterized. It can be grafted onto polyethylene molecules during the cross-linking processes to promote stability of the aromatic voltage stabilizers in XLPE. Fourier transform infrared spectroscopy confirmed that VPE was successfully grafted onto XLPE, and effectively inhibited thermal migration. Thermogravimetric analysis showed that the grafted VPE/XLPE composite exhibits a better thermal stability than a VPE/PE blend composite. Evaluation of the electrical properties showed that the breakdown strength and electrical tree initiation voltage of the VPE/XLPE composite were increased by 15.5% and 39.6%, respectively, when compared to those of bare XLPE. After thermal aging, the breakdown strength and electrical tree initiation voltage of the VPE/XLPE composite were increased by 9.4% and 25.8%, respectively, in comparison to those of bare XLPE, which indicates that the grafted voltage stabilizer can effectively inhibit its migration and enhance the stability of the composite material.

Epoxy-Based Dielectric Materials for Solid Insulator: Preparation, Dielectric Properties, and Breakdown Performance

2013 ◽  
Vol 798-799 ◽  
pp. 197-200
Author(s):  
Nan Li ◽  
Wei Deng ◽  
Hui Gang Sun
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Epoxy Matrix ◽  
Breakdown Strength ◽  
Dielectric Material ◽  
Dielectric Materials ◽  
The Other ◽  
Mixing Ratio ◽  
Solid Insulator ◽  
Polymeric Samples

In this article, epoxy-based dielectric materials for solid insulator were investigated. First, epoxy-based polymeric samples with different permittivities were prepared by incorporating a mixture of two fillers (Al2O3 and SrTiO3) into epoxy matrix. Then, dielectric properties were characterized for the epoxy-based samples by using a dielectric spectrometer with varied frequency. Finally, breakdown tests were performed under AC voltage to characterize the breakdown strength of the dielectric material. Results indicated that the permittivity (dielectric constant) of epoxy-based materials can be adjusted only by changing the mixing ratio of two types of fillers. On the other hand, the obtained dielectric materials showed acceptable breakdown strength with the present amounts of fillers.

scholarly journals Enhanced dielectric properties and breakdown strength of polymer/carbon nanotube composites by coating an SrTiO3 layer

e-Polymers ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 272-278
Author(s):  
Ruolin Han ◽  
Yuping Liu ◽  
Jinchao Shi ◽  
Guang-Xin Chen ◽  
Qifang Li
Keyword(s):  
Dielectric Properties ◽  
Breakdown Strength ◽  
Dielectric Material ◽  
Sol Gel ◽  
Filler Loading ◽  
Filler Concentration ◽  
Dielectric Ceramic ◽  
Nanotube Composites ◽  
Loading Amount ◽  
High Dielectric

Abstract In this work, strontium titanate (STO) was coated on the surface of carbon nanotubes (MWCNTs) through a sol–gel method to form a core–shell structure hybrid powder (STO@MWCNTs). This powder was then added to polydimethylsiloxane to prepare a flexible high-K composite. As coating, STO effectively prevents the overlap and agglomeration of MWCNTs, thereby passivating the percolation threshold of the composite. STO increases the dielectric properties of the composite as a high dielectric ceramic. Under a low filler loading amount of 11 wt%, the dielectric constant and dielectric loss of the composite are 53 and 0.1, respectively. In addition, the composite can still maintain superior breakdown strength and mechanical properties, given the relatively low filler concentration. The enhanced dielectric properties, breakdown strength, and tensile strength make the composite suitable for application as dielectric material in flexible and stretchable energy storage equipment.

Dielectric properties of Ba0.97Bi0.02TiO3–Ba1−xMgxSn0.02Ti0.98O3 composite ceramics

2016 ◽  
Vol 30 (29) ◽  
pp. 1650363
Author(s):  
Jing wang ◽  
Guijuan Rong ◽  
Liangbin Hao ◽  
Lan Gao ◽  
Haiyan Cheng ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Breakdown Strength ◽  
Dielectric Strength ◽  
Dielectric Behavior ◽  
Composite Ceramics ◽  
Solid State Method ◽  
Composition Formula ◽  
State Method ◽  
Mg Content

A wet solid-state method was used in this work to produce [Formula: see text]–[Formula: see text] materials. By using core-shell structure nanocubic [Formula: see text] (BMST) decorated [Formula: see text] (BBT) assemblies, a composite capacitor with improved dielectric constant and enhanced breakdown strength was successfully fabricated in contrast with the composite ferroelectric [Formula: see text]–[Formula: see text] (BBT–BST) ceramic. With increasing Mg content, the ceramic capacitors display a stronger performance in its dielectric behavior. The best dielectric properties were obtained in the composition [Formula: see text] = 0.007 with the dielectric constant above 65,000. The dielectric strength of the ceramics was measured by a withstanding voltage tester. The best dielectric strength was achieved in the composition [Formula: see text] = 0.007 with [Formula: see text] = 5.455 kV/mm.

scholarly journals Dielectric Constant Enhancement with Low Dielectric Loss Growth in Graphene Oxide/Mica/Polypropylene Composites

2021 ◽  
Vol 5 (2) ◽  
pp. 52
Author(s):  
Chao-Yu Lee ◽  
Chia-Wei Chang
Keyword(s):  
Dielectric Constant ◽  
Graphene Oxide ◽  
Dielectric Loss ◽  
Energy Density ◽  
Breakdown Strength ◽  
Dielectric Material ◽  
Dielectric Strength ◽  
Self Healing ◽  
Organic Thin Film ◽  
Low Dielectric

Polypropylene has been widely used as dielectric material in organic thin-film capacitors due to their high breakdown strength, low dielectric loss and self-healing capability. However, polypropylene’s energy density is relatively low. Increasing the energy density of polypropylene by adding materials with a high dielectric constant is commonly used. Still, it often leads to an increase in dielectric loss, lower dielectric strength and other shortcomings. In this study, a thin 2D platelet of mica/graphene oxide composite material was made from exfoliated mica as a substrate and attached by graphene oxide. The mica/graphene oxide platelets were added to polypropylene to make a plastic dielectric composite. The non-conductive flat inorganic additive can increase the dielectric constant and dielectric strength of the composite without increasing dielectric loss. The tiny mica/graphene oxide platelets can significantly improve the dielectric properties of polypropylene. The results show that by adding a small amount (less than 1 wt%) mica/graphene oxide, the relative dielectric constant of polypropylene can increase to more than 3.7 without causing an increase in dielectric loss and the dielectric strength of polypropylene can also enhance.

scholarly journals Investigation of the functional network modifier loading on the stoichiometric ratio of epoxy resins and their dielectric properties

2021 ◽  
Author(s):  
Istebreq A. Saeedi ◽  
Sunny Chaudhary ◽  
Thomas Andritsch ◽  
Alun S. Vaughan
Keyword(s):  
Glass Transition ◽  
Dielectric Properties ◽  
Electrical Properties ◽  
Epoxy Resins ◽  
Functional Network ◽  
Cross Linking ◽  
Network Modifier ◽  
Epoxy Resin System ◽  
The Cross ◽  
The Impact

AbstractReactive molecular additives have often been employed to tailor the mechanical properties of epoxy resins. In addition, several studies have reported improved electrical properties in such systems, where the network architecture and included function groups have been modified through the use of so-called functional network modifier (FNM) molecules. The study reported here set out to investigate the effect of a glycidyl polyhedral oligomeric silsesquioxane (GPOSS) FNM on the cross-linking reactions, glass transition, breakdown strength and dielectric properties of an amine-cured epoxy resin system. Since many previous studies have considered POSS to act as an inorganic filler, a key aim was to consider the impact of GPOSS addition on the stoichiometry of curing. Fourier transform infrared spectroscopy revealed significant changes in the cross-linking reactions that occur if appropriate stoichiometric compensation is not made for the additional epoxide groups present on the GPOSS. These changes, in concert with the direct effect of the GPOSS itself, influence the glass transition temperature, dielectric breakdown behaviour and dielectric response of the system. Specifically, the work shows that the inclusion of GPOSS can result in beneficial changes in electrical properties, but that these gains are easily lost if consequential changes in the matrix polymer are not appropriately counteracted. Nevertheless, if the system is appropriately optimized, materials with pronounced improvements in technologically important characteristics can be designed.

scholarly journals Study of electric field stress on the surface contour and at the triple junction in three phase GIS with FGM spacer under the depression defect

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Janaki Pakalapati ◽  
Venkata N. Kumar Gundavarapu ◽  
Deepak Chowdary Duvvada ◽  
Sravana Kumar Bali
Keyword(s):  
Electric Field ◽  
Triple Junction ◽  
Dielectric Strength ◽  
Functionally Graded ◽  
Uniform Electric Field ◽  
Filler Materials ◽  
Field Stress ◽  
As Doping ◽  
Three Phase ◽  
Graded Material

AbstractNow days, the establishment of spacers is in wide usage in three-phase Gas Insulated Busduct (GIB) for providing mechanical support and better insulation to the conductors. The region of the intersection of SF6 gas, enclosure end and the spacer is one of the weakest links in GIB, so the major concentration is done on minimization of electric field stress at this junction by using Functionally Graded Material (FGM) technique. The other incidents of insulation failures are due to several defects like depression, delamination etc. reduces the dielectric strength of the spacers. In this paper, an FGM post type spacer has been designed for a three-phase GIB under depression and further electric field stress at Triple Junction (TJ) is reduced by introducing a metal insert (MI) nearer to the TJ. Several filler materials are used as doping materials for obtaining different permittivity values using FGM technique to achieve uniform electric field stress. Simulation is carried out for the designed spacer at various operating voltages with different types of FGM gradings. The effect of depression with different dimensions and positions is analyzed before and after inserting MI to the FGM post type spacer in three-phase GIB.

scholarly journals Effects of Interfacial Charge on the DC Dielectric Properties of Nanocomposites

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Jiaming Yang ◽  
Congji Liu ◽  
Changji Zheng ◽  
Hong Zhao ◽  
Xuan Wang ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Breakdown Strength ◽  
Interface Layer ◽  
Low Density Polyethylene ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Effects ◽  
Dielectric Performance ◽  
Positive Effect ◽  
Interfacial Charge

The interfacial charge phenomenon of MgO/low-density polyethylene (LDPE) and SiO2/LDPE nanocomposites was measured by synchrotron radiation small-angle X-ray scattering. Based on the Porod theory, the Porod curve of SiO2/LDPE nanocomposite shows negative divergence but the LDPE and MgO/LDPE do not, which reveals that interfacial charge may exist in the SiO2/LDPE nanocomposite. The DC dielectric properties of the nanocomposites are closely related to the interfacial charge. Experimental results show that the SiO2/LDPE nanocomposite has lower DC conductivity, less space charge, and higher DC breakdown strength than the MgO/LDPE nanocomposite. It is thought that the interfacial charge has a positive effect on the DC dielectric performance of nanocomposites, and the mechanism could be attributed to the scattering effects of the interfacial charge on the carrier migration. There is no obvious interfacial charge in the MgO/LDPE nanocomposite, but it still has excellent DC dielectric properties compared with LDPE, which indicates that the interfacial charge is not the only factor affecting the dielectric properties; the dipole interface layer and the reduction of free volume can also inhibit the migration of carriers and decrease electrons free path, improving the dielectric performance.

The Elastic-Viscoelastic Correspondence Principle for Functionally Graded Materials, Revisited

2003 ◽  
Vol 70 (3) ◽  
pp. 359-363 ◽  
Author(s):  
S. Mukherjee ◽  
Glaucio H. Paulino
Keyword(s):  
Functionally Graded Materials ◽  
Functionally Graded Material ◽  
Correspondence Principle ◽  
Functionally Graded ◽  
Graded Materials ◽  
One Dimensional ◽  
Space And Time ◽  
Graded Material ◽  
Nonhomogeneous Materials ◽  
Exponentially Graded

Paulino and Jin [Paulino, G. H., and Jin, Z.-H., 2001, “Correspondence Principle in Viscoelastic Functionally Graded Materials,” ASME J. Appl. Mech., 68, pp. 129–132], have recently shown that the viscoelastic correspondence principle remains valid for a linearly isotropic viscoelastic functionally graded material with separable relaxation (or creep) functions in space and time. This paper revisits this issue by addressing some subtle points regarding this result and examines the reasons behind the success or failure of the correspondence principle for viscoelastic functionally graded materials. For the inseparable class of nonhomogeneous materials, the correspondence principle fails because of an inconsistency between the replacements of the moduli and of their derivatives. A simple but informative one-dimensional example, involving an exponentially graded material, is used to further clarify these reasons.

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