Dielectric Relaxation of Natural Rubber Vulcanizates

1951 ◽  
Vol 24 (2) ◽  
pp. 320-327 ◽  
Author(s):  
A. Schallamach
Keyword(s):  
Relaxation Time ◽  
Dielectric Loss ◽  
Natural Rubber ◽  
Dielectric Relaxation ◽  
Loss Tangent ◽  
Dielectric Loss Tangent ◽  
Dielectric Relaxation Time ◽  
Different Types ◽  
Cross Links ◽  
Natural Rubber Vulcanizates

Abstract The dielectric loss tangent of different types of vulcanizates of natural rubber has been measured as function of the frequency. Comparisons of the losses in different vulcanizates containing the same amount of combined sulfur show that they decrease with increasing modulus, and it is suggested that the dielectric loss is mostly due to sulfur which has been combined in forms other than cross-links. The dielectric relaxation time is approximately an exponential function of the percentage of combined sulfur. It has been found that moisture increases the audiofrequency losses in rubber more than the radiofrequency losses.

Electrophysical properties of mixtures of mineral oil and synthetic ester dielectric liquid

2021 ◽  
Vol 14 (2) ◽  
pp. 132-141
Author(s):  
M. N. Lyutikova ◽  
S. M. Korobeynikov ◽  
A. A. Konovalov
Keyword(s):  
Dielectric Loss ◽  
Breakdown Voltage ◽  
Loss Tangent ◽  
Dielectric Loss Tangent ◽  
Kinematic Viscosity ◽  
Mineral Oil ◽  
Flash Point ◽  
Power Transformers ◽  
Synthetic Ester ◽  
Insulating Properties

Power transformers are key equipment in power generation, transmission, and distribution systems. The reliability of power transformers is based on the performance of the insulation system, which includes solid cellulose insulation and a liquid dielectric. Modern power engineering requires liquid insulation to have excellent insulating properties, high fire resistance, and biodegradability. Mineral oil that has been in use for over 100 years does not meet certain requirements. Therefore, various methods of enhancing the insulating properties of the oil are currently being considered, including mixing it with other liquid dielectrics, which have excellent properties. Synthetic and natural esters are considered as alternative fluids.This article discusses the possibility of enhancing the insulating characteristics of mineral oil with a high content of aromatic hydrocarbons (for example, T-750 oil) by mixing it with synthetic ester Midel 7131. Assessment is given of insulating parameters of the resulting mixtures with an ester fraction in mineral oil from 0% to fifty%. The main characteristics of the mixtures are described, such as density, kinematic viscosity, flash point, dielectric loss tangent, relative dielectric permittivity, breakdown voltage, and moisture content. It is shown that with an increase in the proportion of ester, some parameters of the obtained insulating liquid improve (flash point, dielectric constant, breakdown voltage), while values of other parameters (density, kinematic viscosity, dielectric loss tangent) with an ester content of more than 10% in the mixture do not meet the requirements for mineral oils.

Method of calculating the dielectric loss tangent of binary systems

1987 ◽  
Vol 52 (3) ◽  
pp. 310-312
Author(s):  
G. N. Dul'nev ◽  
D. P. Volkov ◽  
M. V. Dobrochasov
Keyword(s):  
Dielectric Loss ◽  
Loss Tangent ◽  
Dielectric Loss Tangent ◽  
Binary Systems

Dielectric relaxation time and dipole moment of isometric butanols in benzene solutions.

1983 ◽  
Vol 26 (2) ◽  
pp. 77-84 ◽  
Author(s):  
S.M. Khameshara ◽  
M.S. Kavadia ◽  
M.S. Lodha ◽  
D.C. Mathur ◽  
V.K. Vaidya
Keyword(s):  
Dipole Moment ◽  
Relaxation Time ◽  
Dielectric Relaxation ◽  
Dielectric Relaxation Time

Dielectric Relaxation Time Behavior of B-site Hybrid-doped BaTiO3Ceramics

2014 ◽  
Vol 458 (1) ◽  
pp. 56-63 ◽  
Author(s):  
Thanapong Sareein ◽  
Muanjai Unruan ◽  
Athipong Ngamjarurojana ◽  
Supon Ananta ◽  
Rattikorn Yimnirun
Keyword(s):  
Relaxation Time ◽  
Dielectric Relaxation ◽  
Dielectric Relaxation Time ◽  
Time Behavior

Differential Thermal Analysis and Dielectric Studies on Neopentanol under Pressure

1992 ◽  
Vol 47 (11) ◽  
pp. 1127-1134 ◽  
Author(s):  
H. G. Kreul ◽  
R. Waldinger ◽  
A. Würflinger
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Relaxation Time ◽  
Phase Transitions ◽  
Dielectric Relaxation ◽  
Pressure Dependence ◽  
Dielectric Relaxation Time ◽  
Dielectric Studies ◽  
Dielectric Measurements ◽  
Plastic Phase

Abstract Differential thermal analysis (DTA) and dielectric measurements have been performed on 2,2-dimethyl- 1-propanol (neopentanol) up to 200 MPa. Neopentanol exhibits at least one orientationally disordered (ODIC) phase (solid I) that transforms at lower temperatures to a non-plastic phase (solid II). There is evidence of a further ODIC phase denoted as solid I'. The pressure dependence of the phase transitions and the dielectric behaviour up to frequencies of 13 MHz are described. Activation enthalpies and volumes are derived from the dielectric relaxation time and compared with results for other alcohols

scholarly journals Dielectric and electrical properties of Cr substituted Mg ferrites

2015 ◽  
Vol 39 (1) ◽  
pp. 1-12 ◽  
Author(s):  
AKM Zakaria ◽  
Faizun Nesa ◽  
MA Saeed Khan ◽  
SM Yunus ◽  
NI Khan ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
Loss Tangent ◽  
Dielectric Loss Tangent ◽  
Lattice Parameter ◽  
Activation Energies ◽  
X Ray Diffraction ◽  
Constant E ◽  
Cr Concentration ◽  
Academy Of Sciences

The spinel ferrites MgCrxFe2-xO4 (0.0 ? × ?1.0) were prepared through the solid state reaction using conventional ceramic method at 1300°C in air. The homogeneous phase of the ferrite samples was observed from the X-ray diffraction study. Lattice parameter of the samples was found to decrease with increasing Cr concentration in the system obeying Vegard’s law. The ac electrical resistivity, measured as a function of temperature, decreases with the increase of temperature indicating the semiconducting nature of all the samples. The activation energies were calculated and found to decrease with increasing Cr content. The lower activation energies are associated with higher electrical conductivity. With the increase of temperature, dielectric constant (e`) and dielectric loss tangent are observed to be increased; while with the increase of frequency, dielectric constant (e`) and dielectric loss tangent decrease for all the samples.Journal of Bangladesh Academy of Sciences, Vol. 39, No. 1, 1-12, 2015

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