Corona Aging Research Articles

Literature between the Creativity of the Crisis and the Age of Corona

Literature between the Creativity of the Crisis and the Age of Corona

High Electrical and Mechanical Properties Obtained in a Polyimide‐Based Nanocomposite with Sandwich Structure via Multidimensional Design

AbstractAs an excellent polymer material, polyimide (PI) plays an important role in practical applications. However, traditional filler doping modification is hard to simultaneously improve the dielectric properties and mechanical properties of the film. Here, PI–boron nitride (BN) nanosheets/PI–sodium titanate nanotubes (STNs)/PI–BN composite films with sandwich structure are prepared by in situ polymerization and multilayer coating processes, which significantly enhance the electrical and mechanical properties of dielectric films. With only 0.5 wt% fillers doping, the AC breakdown strength of the composite film can reach 183.7 kV mm−1, which is 16.41% higher than that of pure PI. When the filler doping is 1.5 wt%, the corona aging time of the composite film achieves 311.7% higher than that of pure PI film. In addition, the composite film exhibits outstanding elongation at break (58%) and tensile strength (138.92 MPa) performance. The 2D BN of the outer layer and 1D STNs of the middle layer effectively block the injection of charge carriers while improving the internal polarization response. A mechanism related to microstructure and interface is proposed to explain the improvement of electrical and mechanical properties in detail. This work provides a useful idea for the accurate design of high‐performance dielectric films.

Thermography and Machine Learning Analysis of Corona Aging of Silicone Rubber Nanocomposites

Thermography and Machine Learning Analysis of Corona Aging of Silicone Rubber Nanocomposites

Study on Corona Aging Characteristics of Epoxy Resin Under Different Hygrothermal Environments

Study on Corona Aging Characteristics of Epoxy Resin Under Different Hygrothermal Environments

Enhancement of tracking resistance of silicone rubber through charge dissipation and radical capture by fluorosilane-grafted iron oxide

Fluorosilane-grafted iron oxide (F-Fe2O3) was prepared via surface grafting reaction between iron oxide and perfluorooctyltriethoxysilane. The effect of F-Fe2O3 on the tracking resistance (TR) of addition-cured liquid silicone rubber (ALSR) was investigated by the inclined-plane test (IPT), surface potential decay test (SPDT), thermogravimetry (TGA), corona aging test and scanning electron microscopy (SEM). F-Fe2O3 delayed the occurrence of the intensive arc discharge and reduced the number of arc discharges. The corona resistance and TR of ALSR were effectively improved. ALSR/F-Fe2O3 with 0.15 phr F-Fe2O3 content passed the IPT at 4.5 kV, showing an erosion mass of 3.17%. The hydrophobicity and thermal stability of ALSR were also enhanced. The SPDT showed that F-Fe2O3 effectively dissipated charge. The results of thermal stability and corona resistance tests revealed that F-Fe2O3 could capture free radicals generated by the oxidation of methyl side groups of ALSR chains and thus inhibit the thermal degradation of ALSR during the arc discharge. Moreover, the charge dissipation by F-Fe2O3 could diminish the accumulation of charges in ALSR and reduce the damage of charges to the chains during arc discharge. Therefore, the TR of ALSR was enhanced.

Jewish Ethics of Shaming in the Age of Corona

Abstract By early 2020, COVID-19 was spreading around the world. In many countries, efforts to stop the proliferation included quarantining sufferers and those around them, and in some cases even locking down entire civilian populations. A pandemic calls for personal responsibility with regard to obeying authorities’ instructions concerning social distancing, the wearing of masks, and self-isolation after exposure to a corona patient. The idea of shaming people who are violating the regulations is spreading, but there have been only a few attempts to find the proper balance between respecting human dignity and concern for public health. This article surveys the Jewish ethical principles that seek to balance concern for public health with the shame of the individual and suggests that sometimes there will be both ethical and religious justifications for shaming, at other times, it will be forbidden, and on occasion, it will be permissible within certain limits.

Investigation of charge dynamics in the corona‐aged silicone rubber alumina nanocomposite

AbstractThe effect of corona aging on the surface potential dynamics and charge trap characteristics of silicone rubber alumina nanocomposite are examined using surface potential decay measurement. The aging was carried out by exposing the specimens to corona stress generated by a high‐frequency AC multi needle‐plane electrode system. The results show that the addition of alumina filler increases the surface potential decay time and maximum trap energy. A reduction in trap depth is observed with the corona aging, and the addition of alumina filler limits the degradation and change in charge trap distribution. The results of an analysis of the space charge behavior of different nanocomposites and their comparison are presented. The space charge variation analysis was carried out under the applied electric field of 20 kV/mm at room temperature using the pulsed electro‐acoustic technique (PEA). Based on the results, the charge density, electric field, and charge trap distribution were deduced. It is concluded that the space charge concentration and enhancement in the electric field of the aged material increases with aging duration and it is maximum in the case of 60 min corona‐aged pure silicone rubber. Analysis of the recovery of the charge dynamics of the sample after corona discharges at the different time intervals shows that the recovery of trap distribution is faster for a virgin sample and slower for the sample with 5 wt% of alumina.

Understanding the Surface Condition of Silicone Rubber Nanocomposite Due to Corona Aging Using AFM Imaging and LIBS Spectroscopy

Silicone rubber insulators undergo degradation when they are exposed to corona discharges. The present study explores the surface degradation behavior of silicone rubber alumina nanocomposites due to corona aging using high-frequency ac voltage. The electric field distribution on the sample surface during corona aging is simulated using COMSOL. The change in silicone rubber functional group is studied using Fourier transform infrared (FTIR) spectroscopy analysis. The influence of corona aging time on the surface roughness recovery of silicone rubber nano alumina composites is studied using an atomic force microscopy (AFM). The elemental distribution behavior and change in the emission spectra persistence time are analyzed during recovery period of corona-aged silicone rubber nanocomposites using laser-induced breakdown spectroscopy (LIBS) technique. The addition of alumina nanofiller to the silicone rubber improves the resistance to aging due to corona discharge. Loss and recovery of hydrophobic property of silicone rubber due to corona aging were determined using static contact angle measurement. The results show a direct correlation between the contact angle and the surface roughness recovery characteristics. They indicate that the nanocomposite having a 5 wt% alumina content exhibits the highest resistance to corona discharge with least surface damage. Furthermore, fast recovery was observed in the first few hours after corona aging, and most samples eventually regained their properties after about 8 h of recovery time.

Swelling mechanism of silicone coating on insulation of cable accessories

The composite interface of cable and accessories insulation has long been in a complex environment of combined action of electricity, heat and moisture. The interface coating silicone characteristics play a key role in the interface reliability. In this paper, based on coating silicone grease on cable accessories, the effects of thermal, corona and wet aging on the swelling process of silicone grease on the surface of silicone rubber and the variation of silicone rubber properties after swelling were studied. The results showed that thermal aging, corona aging and wet aging accelerated the swelling of silicone grease. Thermal aging increases the diffusion rate of silicone grease in silicone rubber by increasing the relative motion between silicone grease and silicone rubber molecules. Corona aging destroys the crosslinking structure of silicone rubber by strong oxidants such as ozone and high energy charged particles, which promotes the swelling of silicone grease. Humid aging increases the polarity of silicone grease due to water absorption, and water molecules enter the rubber, which leads to deep swelling. Three kinds of aging destroyed the surface morphology of silicone and silicone rubber.

Design of corona aging test device for silicone rubber based on finite element electric field simulation

Design of corona aging test device for silicone rubber based on finite element electric field simulation

Preparation and properties of ODPA-ODA-SDA polyimide film and its application in corona resistance

High-frequency trend of electrical equipment puts forward higher requirements on the dielectric properties of insulating materials, especially under corona ageing environment. Therefore, a facile and effective method for improved corona resistance is essential for the development of high-frequency power systems. In this article, 4,4′-Oxydiphthalic anhydride (ODPA) was chosen as the dianhydride while 4,4′-Diaminodiphenyl ether (ODA) and 4,4′-diaminodiphenyl sulphide (SDA) as diamines. Consequently, thermally imidized ODPA-ODA-SDA copolyimides were synthesized, and the influence of ODPA and SDA on the dielectric properties was discussed. High-frequency corona ageing test was also conducted to investigate the relationship between dielectric properties and the corona resistance. From dielectric frequency spectra analysis, the ODPA-ODA-SDA copolyimide was considered to exhibit the best dielectric properties when SDA accounted for 30% mole fraction of diamine, the dielectric loss of which was 24.03% lower than that of ODPA-ODA at 20 kHz. Meanwhile, the better corona resistance property and mechanical properties were obtained, especially the corona ageing lifetime was 2.26 times higher than that of ODPA-ODA. To further improve the corona resistance property, a series of modified-PI/Al2O3 nanocomposite films based on ODPA-ODA-SDA matrix were prepared by in-situ polymerization. When the content of Al2O3 nanoparticles reached 12 wt%, the thermal stability was improved and the corona ageing lifetime was 6.14 times longer than that of ODPA-ODA. This experiment provides new ideas and directions for reducing mechanical and thermal performance losses as well as achieving high-efficiency corona resistance, which is expected to promote the development of advanced insulating films.

New patterns of learning during the Pandemic Crisis of 2019

Education institutions and learning operations are part of the hardest hits of the Corona pandemic crisis of 2019. In addition to the sudden breakdowns of vital-life sectors and education, the learning and teaching processes knew some disorders and interruptions differently worldwide. Not only that, but also this crisis brought its effects on students and school children; especially concerning their psychological health due to the restrictions of lockdown and social distancing, over and above that these generations have neither precedent with inevitable crisis, nor procedures. Education in the age of Corona is a primary concern and challenge for countries, especially in the light of the unequal levels of alternative solutions to pursue the teaching process regularly and with lesser damages. This article aims to raise awareness about the novel patterns and platforms that have been used globally since the pandemic's emergence. Furthermore, it addresses their effectiveness in large parts of countries. It attempts to assess their performance and compare the extent of responsiveness to these teaching platforms and technologies in different countries. At the end of this suggested contribution, we intend to track the future of these patterns and platforms in the post-corona phase. 
 

Study on Corona Aging Characteristics of Silicone Rubber Material under Different Environmental Conditions

In this article, a silicone rubber-based composite material is selected as the test sample, and a 100-h corona aging test is conducted under different environments using multiple pin-plate electrodes to study the corona discharge characteristics of pin-plate under different humidity, salt fog, and haze environments. The corona aging characteristics of silicone rubber material are analyzed by the static contact angle, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR). The results show that, with the increase in the relative humidity (RH), the frequency and energy of corona discharge increase. The discharge frequency under a haze environment is small, but the number and amplitude of the positive half-cycle pulse are larger. With the increase in RH and the deterioration of the environment, the oxidation degree and hydrophobicity loss rate of the material surface are accelerated, and the material surface damage is also aggravated. The aging characteristics of silicone rubber have a positive correlation with the content of water molecules in the air, some hydrophilic -OH, and acidic -COOH appear on the material surface, leading to the insulation performance decrease. As the aging of silicone rubber deepens, its equivalent transverse relaxation time drop increases, the number of H atoms that become low bond energy state inside increases, and the resistance to corona aging decreases. The results of this article can provide some reference for the evaluation, diagnosis, and production of composite insulators in different regions.

Investigation on Electrical, Thermal, and Mechanical Properties of Silicone Rubber ATH Nanocomposites

In the present study, investigations have been carried out by choosing the nano-sized ATH (30 – 50 nm) particles as filler content in silicone rubber to acquire a deep insight to understand the use of nano ATH fillers in silicone rubber on its performance, to use it as insulation structure as an outdoor insulator. Variation in the surface condition of silicone rubber nanocomposites due to corona aging and the recovery characteristics analysis carried out through contact angle measurement. Nano ATH added in silicone rubber, up to 3 wt% of filler, shows increased dielectric constant with less loss factor. Water droplet-initiated discharges on silicone rubber nano ATH composites under DC voltage measured using UHF technique and the damage caused zone analyzed through AFM studies and by surface potential measurement, which indicates higher surface roughness and increased charge trap depth. It is observed that negative DC voltage has higher CIV followed by positive DC and AC voltage. Laser Induced breakdown studies (LIBS) show a direct correlation between plasma temperature and material surface hardness. Also, on laser shining on the surface of the specimen, its temperature was measured on the backside of the specimen through thermal imaging confirming increased diffusivity of temperature. Laser flash analysis shows a direct correlation between filler content in base polymer and thermal conductivity and diffusivity. Higher storage modulus and activation energies measured from the dynamic mechanical analysis indicate the significance of prepared composites as an excellent mechanical support structure for the power system network.

Aging Assessment of Corona-Exposed HTV-SiR/EPDM Blends Loaded With Nanofillers

Exposure of insulating systems to strong electric field and other environmental stresses may cause loss of their desired properties. In high-voltage applications, phenomena, such as corona discharges and unexpected flashovers, may deteriorate the surface as well as bulk conditions of an insulating material and thereby affect its lifetime. In this article, several types of corona-exposed HTV-SiR/ethylene propylene diene monomer (EPDM) blends filled with different concentrations of nano-sized boron nitride and silicon carbide particles are evaluated and the induced modifications of their properties are presented and discussed. The diagnosis is based on measured data of surface partial discharge (PD) and volume current. For the latter, experiments were performed at different levels of electric field between 0.5 and 4 kV/mm and ambient temperature ranging from 22 °C to 70 °C. Results of the conducted experiments revealed the degradation of surface properties through an increase in the PD magnitude. It was also observed that corona aging of the samples decreases the threshold electric field particularly at elevated temperatures, above which space charge effect in the materials may become significant. Moreover, it was observed that the blend compositions loaded with nanofillers retard surface PD and bulk deterioration.

Literature between the Creativity of the Crisis and the Age of Corona..

Literature between the Creativity of the Crisis and the Age of Corona..

Random Pandemic Perambulations: A Brief History of Literary Walks in the Age of Corona

This article focuses on the concept of randomness as the absence of goal-oriented movement in literary walks. The literature of walking displays the happenstance of adventure as one of the great antidotes to our inane, highly technologized, digitalized twenty-first-century lifestyle. In the end, however, such randomness may reveal itself as not so random after all, as the purpose of the journey, its inherent telos, discloses itself while travelling or in hindsight. This article provides brief glimpses into the history of literary walks to examine this tension between apparent randomness and the non-random. By drawing on a range of cultural theories and theorizations of travel and especially of walking, I look at literary foot travel in the nineteenth century, the Romantics and American Transcendentalists, some great adventure hikes in the twentieth and twenty-first centuries, and the urban and rural flâneur. In doing so the article does not lose sight of the question of how we can instrumentalize the literature of walking for life during the current pandemic.

Microstructure and Electrical Properties of Fluorene Polyester Based Nanocomposite Dielectrics

As a new type of dielectric material, the low dielectric constant and corona resistance life of fluorene polyester (FPE) restricts the range of its applications. In order to simultaneously achieve a high dielectric constant and the long corona aging lifetime of FPE, SiO2 nanoparticles were chosen as additive to prepare FPE-based composite films. The microstructure of the composite film was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), infrared spectroscopy (IR) and small-angle X-ray scattering (SAXS). The dielectric performances of the composites, including the dielectric constant, breakdown strength and corona resistance lifetime, were investigated. The results show that the introduced SiO2 does not destroy the structure of the FPE molecular chain and that it increases the thickness of the filler-matrix interface. The dielectric constant of SiO2/FPE composites increased from 3.54 to 7.30 at 1 Hz. Importantly, the corona resistance lifetime increased by about 12 times compared with the pure FPE matrix. In brief, this work shows what possibilities there might be when considering the potential applications of high-strength insulating materials.

Investigation on Surface Condition of the Corona-Aged Silicone Rubber Nanocomposite Adopting Wavelet and LIBS Technique

Silicone rubber nanocomposites were prepared using 1, 3, 5, and 10 wt% of alumina nanofiller. Corona inception voltage (CIV) due to water droplets was measured using fluorescence technique, and it has decreased for alumina-added silicone rubber nanocomposites and with corona-aged samples. The effect of the corona discharges on the surface morphology characteristics of the nanocomposites was analyzed by measuring contact angle, surface profile measurement using atomic force microscopy (AFM), and characterized by adopting multiresolution signal decomposition (MRSD) technique. The addition of the alumina nanofiller suppressed the surface roughness for the corona-aged nanocomposites and 5-wt% sample observed to have the lowest surface roughness values. Recovery of the surface roughness caused by corona discharges was analyzed at different time intervals, and it was observed that alumina nanoparticle-added silicone rubber showed an incremental reduction in the roughness recovery rate. The laser-induced breakdown spectroscopy (LIBS) technique was adopted to analyze the nanocomposites after the corona aging, and further plasma temperature was evaluated at different recovery times. The addition of an alumina nanofiller increased the plasma temperature, and 5-wt% samples have the lowest plasma temperature recovery rate after corona aging. The analysis of the study indicates that the corona-aged silicone rubber specimen surface properties recover in 8 h of resting time period.

War and peace in the age of corona: an analysis of support for repressive state policies in divided societies

ABSTRACT Unlike various natural disasters that some studies have highlighted as potential contributors to peace, the threat posed by the COVID-19 pandemic is neither short-term nor regionally confined. Thus, rather than invoking a compassionate response, the pandemic is likely to aggravate pre-existing divisions and create an environment that accentuates survival over compassion. Building on a large probability survey data gathered in May 2020 in Turkey, we demonstrate that the pandemic has disproportionally affected minority Kurds and exacerbated pre-existing inequalities and social polarization. Results from a series of regression analyses show growing dissatisfaction with the Turkish government’s handling of the pandemic. However, this effect fails to translate into the sense of solidarity between majority Turks and minority Kurds necessary to build a peaceful society. Support for the government’s approach to the Kurdish opposition seems to be conditioned by social categorization and increasingly partisan political identities in Turkey.