THE DISCONTINUITY IN THE DIELECTRIC CONSTANT OF LIQUIDS AND THEIR SATURATED VAPORS AT THE CRITICAL TEMPERATURE

1935 ◽  
Vol 13b (5) ◽  
pp. 296-307 ◽  
Author(s):  
J. Marsden ◽  
O. Maass
Keyword(s):  
Dielectric Constant ◽  
Critical Temperature ◽  
Methyl Ether ◽  
Temperature Region ◽  
Room Temperature ◽  
Saturated Vapor ◽  
Dielectric Constants ◽  
Large Temperature ◽  
Critical Temperatures ◽  
Dielectric Cell

A dielectric cell, which is specially adapted to a study of the dielectric constants of liquid and gas over a large temperature range, including the critical temperature region, is described. The dielectric constants of methyl ether (liquid and saturated vapor) and propylene (liquid and saturated vapor), from room temperature to eight degrees above the critical temperatures, are given. The measurements show that the dielectric constants of liquid and gas are not identical at the critical temperature. These results are in agreement with previous work carried out in this laboratory on the discontinuity in properties of the medium above and below the point of disappearance of the meniscus.

THE POLARIZATION OF LIQUIDS AND THEIR SATURATED VAPORS IN THE CRITICAL TEMPERATURE REGION

1936 ◽  
Vol 14b (3) ◽  
pp. 90-95
Author(s):  
J. Marsden ◽  
O. Maass
Keyword(s):  
Critical Temperature ◽  
Methyl Ether ◽  
Temperature Region ◽  
Room Temperature ◽  
Saturated Vapor ◽  
Dielectric Constants

The values of the so-called polarization of methyl ether (liquid and saturated vapor) and propylene (liquid and saturated vapor), from room temperature to the critical temperature, are given. In both liquids this polarization is independent of the temperature to within a few degrees of the critical temperature. Calculations show that the polarizations of a liquid and its saturated vapor may be equal above the critical temperature, even though the dielectric constants of the liquid and its saturated vapor, as well as their densities, are different.

scholarly journals Huge values of room-temperature dielectric constants in pellets of poly(3-methylthiophene)

2004 ◽  
Vol 19 (7) ◽  
pp. 2068-2071
Author(s):  
S. Moraes ◽  
L. Walmsley ◽  
E.C. Pereira ◽  
A.A. Correa
Keyword(s):  
Dielectric Constant ◽  
Charge Density Wave ◽  
Room Temperature ◽  
Density Wave ◽  
Low Frequency ◽  
Temperature Data ◽  
Dielectric Constants ◽  
Wave Characteristic ◽  
Rc Circuit ◽  
A Charge

Room temperature data of impedance and phase angle in pellets of electrochemically synthesized ClO4− doped poly(3-methylthiophene) (P3MT) were analyzed assuming the sample being represented by a parallel resistor-capacitor (RC) circuit or by a series RC circuit. The last assumption proved to be the correct one, and to confirm it we use the sample as the RC component of a resistor-capacitor-inductor series resonator. We discuss the possibility of this RC series behavior to be due to a charge-density wave characteristic also evidenced from the huge values of the low-frequency dielectric constant of the system.

THE VARIATION OF THE VISCOSITY OF GASES WITH TEMPERATURE OVER A LARGE TEMPERATURE RANGE

1935 ◽  
Vol 13b (3) ◽  
pp. 140-148 ◽  
Author(s):  
A. B. Van Cleave ◽  
O. Maass
Keyword(s):  
Carbon Dioxide ◽  
High Temperatures ◽  
Methyl Ether ◽  
Sulphur Dioxide ◽  
Low Temperatures ◽  
Room Temperature ◽  
Empirical Equation ◽  
Large Temperature ◽  
Temperature Range ◽  
Inversion Temperature

The coefficients of viscosity of ammonia, propylene, ethylene and methyl ether, over the temperature range 23 to −80 °C., have been measured. A comparison is made between the present data and those of other authors for temperatures above 0 °C. It is estimated that the authors' results are correct to 0.2% and have a relative accuracy of 0.1%. It is claimed that they are the most accurate data for the viscosity of gases at low temperatures to date.The validity of a number of viscosity–temperature relations has been tested with the present data and those previously published (18, 20). In general, it is found that the equations of Sutherland and Jones hold at high temperatures but fail at low temperatures for substances such as carbon dioxide, sulphur dioxide, ammonia, methyl ether and propylene, which have viscosity–temperature curves that are convex to the temperature axis below room temperature. An empirical equation is suggested which adequately represents the variation of viscosity with temperature for these five gases over the temperature range 23 to −80 °C. However, this relation fails at high temperatures for all gases, and even at low temperatures for substances such as hydrogen, air and ethylene.It is pointed out that the viscosity–temperature curves for carbon dioxide, sulphur dioxide, ammonia, methyl ether and propylene each show a definite inversion or inflexion point. Below this inversion temperature the viscosity curves are convex to the temperature axis; above it they are concave to the temperature axis. In general, it seems that this inversion temperature bears a direct relation to the polarity of the molecule and to the critical temperature.

Preparation and Dielectric Properties of Cu/PVDF Composite Films

2014 ◽  
Vol 1035 ◽  
pp. 417-421 ◽  
Author(s):  
Jian Wen Zhai ◽  
Ya Jun Wang ◽  
Jian Lou Deng ◽  
Chang Gen Feng
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Room Temperature ◽  
Volume Fraction ◽  
Composite Films ◽  
Interfacial Polarization ◽  
Dielectric Constants ◽  
Pvdf Film ◽  
Continuous Increase ◽  
Better Than

nanoand micro size Cu were employed separately and investigated comparatively. Different volume fraction of Cu was added into PVDF film in order to investigate the content of filler effect on the dielectric properties of polymer composites. XRD and SEM were used to analyze the crystalline phase and microstructure of the films. The results show that two sizes of Cu have the same peak features, and with the continuous increase of the content of Cu, it disperse better in PVDF. The dielectric constant (ε) of the composite containing 16 vol% micro-CCTO filler is 16 at 100 Hz and room temperature, and its dielectric loss (tanδ) is only 0.15, which is substantially better than others. Besides, for 18 vol% nanoCu/PVDF composite tanδis 0.25 andεis 18 at 100 Hz. Moreover,εand tanδof nanoCu/PVDF composite are both higher than those of micro-Cu/PVDF. Analysis shows that the composites with nanoCu have higher dielectric constants, which is mainly from the interfacial polarization.

Synthesis and Characterization of Azobenzene-Containing Polydiacetylene Polymers

2014 ◽  
Vol 976 ◽  
pp. 46-51
Author(s):  
Esthela Albarrán Preza ◽  
Enrique Vigueras-Santiago ◽  
Susana Hernández López
Keyword(s):  
Dielectric Constant ◽  
Room Temperature ◽  
Main Chain ◽  
Dielectric Constants ◽  
Electronic Density ◽  
Polar Species ◽  
Acceptor Group ◽  
Covalently Bonded ◽  
Donor Acceptor

Polydiacetylenes are a type of highly conjugated polymers, and highly polar species are obtained when these polymers contain donor-acceptor azobenzene entities. In this paper the synthesis, characterization and evaluation of the dielectric constant of two polydiacetylenes containing azobenzenes as pendant groups are discussed. The Azobenzene chromophores are covalently bonded to the main chain, and their polarity is defined by an electro-donor (amine) and an electro-acceptor group (nitro or chlorine) bonded to the ends of a conjugated azobenzene structure. Both polymers were processed into plates of 1cm diameter x 0.674 mm thickness using a thermo mechanic technique. Their dielectric constants were evaluated respect to the temperature in a range of frequency of 110 MHz-1.32 GHz, from room temperature to close to their respective Tg. The dielectric constant for the polymer containing the nitro group was higher than it for polymer containing the chloride atom at all temperatures. It is discussed in terms of the ability to nitro and chloride to attract electronic density.

scholarly journals Porous and Nonporous Film-Shaped Magnetorheological Nanocomposites: Dielectric and Electrical Properties

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Aref Naimzad ◽  
Yousef Hojjat ◽  
Mojtaba Ghodsi
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
Room Temperature ◽  
Volume Resistivity ◽  
Comparative Investigation ◽  
Dielectric Constants ◽  
Dielectric Losses ◽  
Iron Particles ◽  
Electrical And Dielectric Properties

This paper presents a brief experimental comparative study on electrical and dielectric properties of two sets of porous and nonporous MRNCs, each including five samples of film-shaped magnetorheological nanocomposites (MRNCs) based on room temperature vulcanized (RTV) silicone rubber and nanosized carbonyl iron particles (CIPs). The electrical and dielectric properties of porous and nonporous MRNCs were measured at five different filler concentrations. Several experiments were performed to measure the volume resistivity, dielectric constant, and dielectric loss. The MRNCs dielectric properties were analysed with respect to the parameters like frequency and CIPs loadings. The electrical conductivity was studied in terms of volume resistivity. The comparative investigation suggests the porous MRNCs for smart and light-weighted structures those benefits from a lower electrical property, dielectric losses, and dielectric constants.

High Temperature Dielectric Constants of Rubidium Halides

1972 ◽  
Vol 50 (10) ◽  
pp. 1053-1054 ◽  
Author(s):  
Suresh Chandra ◽  
Jai Prakash
Keyword(s):  
Dielectric Constant ◽  
High Temperature ◽  
Melting Point ◽  
Standing Wave ◽  
Room Temperature ◽  
Dielectric Constants ◽  
Wave Technique

The high temperature dielectric constants of RbCl, RbBr, and RbI are measured at 24.6 GHz from room temperature to near melting point. A standing wave technique has been used. The dielectric constant of RbBr is observed to increase at a faster rate than that of RbCl and RbI.

THE LIQUID DENSITIES OF PROPYLENE AND METHYL ETHER AS DETERMINED BY A MODIFIED DILATOMETER METHOD

1936 ◽  
Vol 14b (3) ◽  
pp. 96-104 ◽  
Author(s):  
D. B. Pall ◽  
O. Maass
Keyword(s):  
Critical Temperature ◽  
Methyl Ether ◽  
Corresponding States ◽  
Large Temperature ◽  
Temperature Range ◽  
Law Of Corresponding States ◽  
The Law

A modification of the dilatometer method for measuring the density of liquids which can be applied over a large temperature range and up to the region of the critical temperature is described. The densities of methyl ether and propylene have been measured over the temperature range 7°–120 °C. and 20°–88 °C. respectively, with an accuracy of 1 part in 2000. A comparison is made with the data of other investigators. Application of the data to the law of corresponding states shows that the law holds to within the accuracy attained up to temperatures at least 0.96 of the critical.

Dielectric constants of ionic crystals and their variations with temperature and pressure

1970 ◽  
Vol 316 (1526) ◽  
pp. 351-375 ◽  
Keyword(s):  
Dielectric Constant ◽  
Room Temperature ◽  
Dielectric Constants ◽  
The Self ◽  
Ionic Crystals ◽  
Long Wave ◽  
Ionic Compounds ◽  
Transverse Optic ◽  
Temperature And Pressure ◽  
Thallium Halides

Measurements of the audio- and radio-frequency dielectric constants of the alkali and thallium halides have been made over the range of temperature 1.5 to 350 K and at pressure up to 4 kbar (400 MN m -2 ), on crystals of high purity. The results are used to separate, for each compound, that part of the variation in dielectric constant which is explicitly dependent on temperature from that part which is explicitly dependent on volume. The observed variations at constant temperature are used to provide measures of the Gruneisen parameters for the long-wave transverse-optic phonons, and the variations at constant volume are discussed in terms of the anharmonic self-energies of these phonons. The materials studied here are all simple highly ionic compounds but, at room temperature, the self-energies of some prove to be positive while for others they are negative. It is shown how this can be interpreted in terms of competing three-phonon and four-phonon decay and scattering processes.

Dielectric Property of NaCu3Ti3NbO12 Ceramics Doped with Small Amount MgO Nanopowder

2016 ◽  
Vol 675-676 ◽  
pp. 93-96
Author(s):  
Wilai Chomchai ◽  
Chompoonuch Warangkanagool
Keyword(s):  
Dielectric Constant ◽  
Dwell Time ◽  
Room Temperature ◽  
Sintered Sample ◽  
Dielectric Constants ◽  
Distilled Water ◽  
Green Body ◽  
Impedance Analyzer ◽  
Pure Phase ◽  
Scanning Electron

In this study, the NaCu3Ti3NbO12 ceramics + (0-0.5 vol%)MgO nanopowder were prepared by solid state reaction. The precursors were ball milled for 24 hours and calcined at 700-1000°C. Selected the calcinations temperature with calculate pure phase from XRD results. The powders on selected temperature were various dwell time for 2-24 hours. The optimum calcination condition for NaCu3Ti3NbO12 powder is 950°C for 24 hours. The calcined powders were doped with small amounts of MgO nanopowder and pressed into a disc shape. Sinter the green body at 975-1025°C for 10 hours. Microstructure and density were examined by scanning electron microscope (SEM) and Archimedes method with distilled water as the fluid, respectively. The rectangular grain and normal grain growth are observed. The highest relative density of NaCu3Ti3NbO12 ceramics + (0-0.5 vol%)MgO nanopowder sintered at 1000°C are close to 90%. An impedance analyzer was also used to measure the dielectric constant (εr) of 1000°C sintered sample at room temperature. The doping of small amounts of MgO nanopowder to make improved NaCu3Ti3NbO12 ceramic dielectric constants and the optimum condition for doping MgO nanopowder is 0.1 vol%.

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