scholarly journals Volume Resistivity of Viton Polymer under Thermal Aging

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 773
Author(s):  
Alireza Abdihamzehkolaei ◽  
Md Tanvir Ahad ◽  
Zahed Siddique
Keyword(s):  
Surface Morphology ◽  
Resistivity Measurement ◽  
Accelerated Aging ◽  
Natural Aging ◽  
Poor Performance ◽  
Volume Resistivity ◽  
Detailed Comparison ◽  
Aged Sample ◽  
Electrical Parameters ◽  
Transient Effect

This study examines the influence of various electrical parameters on the volume resistivity of the Viton fluoroelastomer. The transient current, the temperature dependence of volume resistivity, the voltage dependence of resistivity, and the surface morphology of Viton insulators are investigated for new and aged specimens. An accelerated aging process has been employed in order to simulate the natural aging of insulators in service. A detailed comparison between the new and aged samples is presented. The transient effect, which is a challenge to the resistivity measurement of insulators, has been investigated. The first 60 s of the resistivity measurement test showed a significant influence from the transient effect and should be excluded from the data. The volume resistivity of both new and aged samples decreased when the temperature increased. However, the resistivity of the aged sample was lower than the new one at all tested temperatures. When the temperature increased from 35 to 190 °C, resistivity decreased from 4.77 × 1010 to 6.99 × 108 Ω-cm for the new sample and from 2.6 × 1010 to 6.68 × 108 Ω-cm for the aged sample under 500 V. Additionally, the results from this study showed that the volume resistivity is inversely proportional to the applied voltage. Finally, scanning electron microscope (SEM) micrographs/images allowed us to closely examine the surface morphology of new and aged Viton samples. The surface of aged samples has been recognized with higher surface roughness and more significant surface cracks leading to poor performance under high voltage applications.

Accelerated Aging of Deacidified and Untreated Book Paper in 1967 Compared with 52 Years of Natural Aging

2020 ◽  
Vol 41 (3) ◽  
pp. 131-152
Author(s):  
Tali H. Horst ◽  
Richard D. Smith ◽  
Antje Potthast ◽  
Martin A. Hubbe
Keyword(s):  
Room Temperature ◽  
Accelerated Aging ◽  
Natural Aging ◽  
Scanning Electron Micrographs ◽  
Surface Ph ◽  
Room Temperature Storage ◽  
Folding Endurance ◽  
Endurance Tests ◽  
Breaking Length ◽  
Temperature Storage

AbstractThree copies of a book that had been optionally deacidified using two different procedures in 1967, and then subjected to accelerated aging, were tested again after 52 years of natural aging. Matched copies of the book Cooking the Greek Way, which had been printed in Czechoslovakia on acidic paper, were evaluated. Nonaqueous treatment of two of the copies with magnesium methoxide dissolved in chlorofluorocarbon solvent had been found in 1967 to have decreased the susceptibility to embrittlement, as evidenced by the results of the accelerated aging, followed by folding endurance tests. Retesting of the same books in 2019, after 52 years of room temperature storage, showed that the deacidification treatments had achieved the following benefits in comparison to the untreated book: (a) higher brightness; (b) higher folding endurance; (c) tensile breaking length higher in the cross-direction of the paper; (d) substantial alkaline reserve content, (e) an alkaline surface pH in the range 7.1–7.4, and (f) higher molecular mass of the cellulose. Remarkably, some of the folding endurance results matched those of unaged samples evaluated in 1967. Scanning electron micrographs showed no differences between the treated and untreated books.

scholarly journals Altered Nuclear Functions in Progeroid Syndromes: a Paradigm for Aging Research

2009 ◽  
Vol 9 ◽  
pp. 1449-1462 ◽  
Author(s):  
Baomin Li ◽  
Sonali Jog ◽  
Jose Candelario ◽  
Sita Reddy ◽  
Lucio Comai
Keyword(s):  
Werner Syndrome ◽  
Accelerated Aging ◽  
Natural Aging ◽  
Aging Research ◽  
Cellular Processes ◽  
Functional Connections ◽  
Age Related ◽  
Progeroid Syndromes ◽  
Progeria Syndrome ◽  
Hutchinson Gilford Progeria Syndrome

Syndromes of accelerated aging could provide an entry point for identifying and dissecting the cellular pathways that are involved in the development of age-related pathologies in the general population. However, their usefulness for aging research has been controversial, as it has been argued that these diseases do not faithfully reflect the process of natural aging. Here we review recent findings on the molecular basis of two progeroid diseases, Werner syndrome (WS) and Hutchinson-Gilford progeria syndrome (HGPS), and highlight functional connections to cellular processes that may contribute to normal aging.

scholarly journals Volume and Surface Resistivity Measurement of Insulating Materials Using Guard-Ring Terminal Electrodes

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2811
Author(s):  
Heon-Gyeong Lee ◽  
Jin-Gyu Kim
Keyword(s):  
Dielectric Breakdown ◽  
Breakdown Strength ◽  
Resistivity Measurement ◽  
Volume Resistivity ◽  
Surface Resistivity ◽  
International Standards ◽  
Guard Ring ◽  
International Electrotechnical Commission ◽  
Renewable Energy Resources ◽  
Insulating Materials

Recently, eco-friendly energy conversion policies have been being promoted through de-nuclearization and de-coal. For this purpose, a super grid should be built to optimize sustainable renewable energy resources such as solar and wind power. Accordingly, considering the various problems such as technology and cost, a system for efficient energy transmission is required. Hence, research is being actively conducted to apply it, owing to the development of the high voltage direct current (HVDC) system. Among HVDC systems, the cable system is extremely important, in addition to the measurement of the dielectric breakdown strength, space charge, and volume resistivity of insulating materials. The existing resistivity measurement method measures both the volume and surface resistivity using a three-terminal electrode that is used in the international standards of American Society for Testing and Materials (ASTM) D 257 and International Electrotechnical Commission (IEC) 60093. However, the circuit configuration differs depending on the measurement of the volume and surface resistivity; moreover, when a DC voltage is applied to the insulator, a charging current flows and there are multiple samples to be measured, which takes a considerable amount of time. Therefore, in this study, we proposed a new type of resistivity measurement system that is based on the existing three-terminal electrode system. Furthermore, we produced a system capable of simultaneously measuring the volume and surface resistivity. Finally, using this system, we compared and analyzed the volume and surface resistivity of five insulating materials.

scholarly journals One-Step Reinforcement and Deacidification of Paper Documents: Application of Lewis Base—Chitosan Nanoparticle Coatings and Analytical Characterization

Coatings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1226
Author(s):  
Zhihui Jia ◽  
Chun Yang ◽  
Fangnan Zhao ◽  
Xiaolian Chao ◽  
Yuhu Li ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Chitosan Nanoparticles ◽  
Antibacterial Properties ◽  
Interaction Mechanism ◽  
Accelerated Aging ◽  
Natural Aging ◽  
Lewis Base ◽  
X Ray ◽  
Chitosan Nanoparticle ◽  
One Step

To delay acidification and deterioration during natural aging, deacidification and reinforcement of paper manuscripts have been the most important technologies to prolong the life of objects. Herein, a novel approach for the conservation of paper manuscripts is proposed using chitosan nanoparticles as Lewis base that leads to both deacidification and strengthening of paper in one-step. Chitosan nanoparticles were prepared through physical ball grinding method and characterized via scanning electron microscopy (SEM), X-ray diffraction (XRD), laser particle size analyzer (LPSA), Fourier transform infrared spectroscopy (FTIR), and atomic force microscope (AFM). To evaluate the resistance of chitosan nanoparticle coating, the mechanical properties of paper after artificial aging were evaluated using dry heat and hygrothermal accelerated aging methods. The SEM, EDX, and X-ray Photoelectron Spectroscopy (XPS) were used to analyze the interaction mechanism between chitosan and Shuxuan paper. The results show that the coated paper had superior durability with respect to pH, tensile strength, and folding endurance. There was a presence of protonated amines in the form of ammonium salts due to ionic bindings with free H+ in the acidified paper, and the remaining –NH2 could be used as a base reserve. Finally, the resulting coated papers displayed good antibacterial properties.

Accelerated Aging of Vulcanized Rubber. Factors Determining the Relation between Oven and Bomb Aging

1947 ◽  
Vol 20 (3) ◽  
pp. 760-768 ◽  
Author(s):  
R. G. Newton ◽  
J. R. Scott
Keyword(s):  
Accelerated Aging ◽  
Natural Aging ◽  
Relative Importance ◽  
Temperature Coefficients ◽  
Vulcanized Rubber ◽  
Relative Response ◽  
Aging Conditions ◽  
Moderate Range ◽  
Natural Rubber Vulcanizates ◽  
Theoretical Considerations

Abstract A study has been made of the influence of the following factors on the relative rates of tensile deterioration of natural rubber vulcanizates in the Geer oven and oxygen bomb, both at 70° C : period of vulcanization, sulfur ratio, nature of accelerator. Expressing this relation as the oven/bomb ratio, i.e., the ratio between oven and bomb aging periods that give the same deterioration, the following conclusions are drawn. (1) Varying the period of vulcanization of a given mix over a moderate range (2:3) around the optimum does not noticeably alter the oven/bomb ratio, except in unaccelerated mixes, where overvulcanization gave an abnormally low ratio, owing to the rubber perishing very rapidly in the oven. (2) The effect of varying the sulfur ratio within the usual limits for soft rubbers is small, and appears to result from the quicker vulcanization of the mixes richer in sulfur. (3) The nature of the accelerator profoundly affects the ratio, values ranging from 3 to 27 being found among the present mixes ; this effect is believed to be exerted through the influence of the accelerator both on rate of vulcanization and on the oxidizability of the vulcanizate. Theoretical considerations indicate that a rubber which vulcanizes quickly and (or) oxidizes slowly should give a low oven/bomb ratio, whereas one that vulcanizes slowly and(or) oxidizes quickly should give a higher ratio. The experimental data are generally in accord with this, and there is evidence that both rate of vulcanization and oxidizability can have an important effect, but the data do not enable the separate effect of each to be assessed exactly. The bearing of the results on the use of the oven and bomb tests is briefly discussed. It is shown that they demonstrate the fallacy of using a single factor for converting oven to bomb aging periods or vice versa, and that the relative natural aging resistances of widely different vulcanizates cannot be reliably assessed by either test, a limitation arising from the fact that the relative importance of oxidative decay and aftervulcanization varies from one type of mix to another, and that the temperature coefficients of these processes are not necessarily the same. These facts are very important in relation to the choice and application of accelerated aging tests for specification purposes, since these usually have to be applied to rubbers of unknown compositions, which are likely to vary widely in their relative response to different aging conditions.

Effect of GaAs (100) substrate misorientation on the electrical parameters and surface morphology of metamorphic In0.7Al0.3As/In0.75Ga0.25As/In0.7Al0.3As HEMT nanoheterostructures

2014 ◽  
Vol 48 (1) ◽  
pp. 63-68 ◽  
Author(s):  
G. B. Galiev ◽  
S. S. Pushkarev ◽  
I. S. Vasil’evskii ◽  
E. A. Klimov ◽  
A. N. Klochkov ◽  
...  
Keyword(s):  
Surface Morphology ◽  
Electrical Parameters

Enhanced mechanical properties in ultrafine grained 7075 Al alloy

2005 ◽  
Vol 20 (2) ◽  
pp. 288-291 ◽  
Author(s):  
Y.H. Zhao ◽  
X.Z. Liao ◽  
Y.T. Zhu ◽  
R.Z. Valiev
Keyword(s):  
Mechanical Properties ◽  
Natural Aging ◽  
Al Alloys ◽  
Coarse Grained ◽  
Tensile Yield Strength ◽  
Al Alloy ◽  
Aged Sample ◽  
Angular Pressing ◽  
7075 Al Alloy ◽  
Ultrafine Grained

Highest strength for 7075 Al alloy was obtained by combining the equal-channel-angular pressing (ECAP) and natural aging processes. The tensile yield strength and ultimate strength of the ECAP processed and naturally aged sample were 103% and 35% higher, respectively, than those of the coarse-grained 7075 Al alloy counterpart. The enhanced strength resulted from high densities of Guinier–Preston (G-P) zones and dislocations. This study shows that severe plastic deformation has the potential to significantly enhance the mechanical properties of precipitate hardening 7000 series Al alloys.

scholarly journals Исследование вольт-амперных характеристик новых гетероструктур MnO-=SUB=-2-=/SUB=-/GaAs(100) и V-=SUB=-2-=/SUB=-O-=SUB=-5-=/SUB=-/GaAs(100), прошедших термическую обработку

2019 ◽  
Vol 53 (8) ◽  
pp. 1074
Author(s):  
Б.В. Сладкопевцев ◽  
Г.И. Котов ◽  
И.Н. Арсентьев ◽  
И.С. Шашкин ◽  
И.Я. Миттова ◽  
...  
Keyword(s):  
Surface Morphology ◽  
Thermal Oxidation ◽  
Current Density ◽  
Chemical Bonding ◽  
Room Temperature ◽  
Reverse Bias ◽  
Electrical Parameters ◽  
Internal Interface ◽  
Current Voltage ◽  
Bias Range

AbstractComplex oxide films with a thickness of about 200 nm are formed during the thermal oxidation of GaAs with magnetron-deposited V_2O_5 and MnO_2 nanolayers. The electrical parameters of the films (reverse-bias breakdown voltage and current density) are determined by the method of current–voltage ( I – V ) characteristics at room temperature in the bias range from –5 to +5 V, and their composition and surface morphology are investigated. It is shown that V_2O_5 facilitates the more intense (in comparison with MnO_2) chemical bonding of arsenic at the internal interface with the formation of As_2O_5. As a result, thermally oxidized V_2O_5/GaAs heterostructures exhibit higher breakdown voltages.

Sign in / Sign up

Export Citation Format

Share Document