DIELECTRIC LOSS AND RELAXATION TIME IN ROSIN

Physics ◽  
1932 ◽  
Vol 2 (2) ◽  
pp. 82-92 ◽  
Author(s):  
J. B. Whitehead
Keyword(s):  
Relaxation Time ◽  
Dielectric Loss ◽  
Dielectric Loss And Relaxation

Microwave Relaxation and Association of 3,5 Dimethyl 3-Hexanol

1970 ◽  
Vol 25 (11) ◽  
pp. 1685-1687
Author(s):  
F. F. Hanna ◽  
K. N. Abd-El-Nour
Keyword(s):  
Dielectric Constant ◽  
Relaxation Time ◽  
Dielectric Loss ◽  
Relaxation Times ◽  
Concentrated Solutions ◽  
Short Relaxation Time

Abstract The dielectric constant (ε′) and dielectric loss (ε′′) of 3,5 dimethyl 3-hexanol in heptane have been measured for dilute and concentrated solutions at five wavelengths between 25 cm and 2 mm and at 20°, 40° and 60 °C. The data have been analysed and two relaxation times are obtained. The long relaxation time is attributed to the rotation of the whole molecule and the short relaxation time to the relaxation of the OH-group. For the range of concentrations used, the results show that associates are hardly detectable.

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.

Dielectric properties of normal, reduced, and specially reduced rutile (TiO2) single crystals at room temperature

1969 ◽  
Vol 47 (1) ◽  
pp. 3-6 ◽  
Author(s):  
H. B. Lal ◽  
K. G. Srivastava
Keyword(s):  
Dielectric Constant ◽  
Relaxation Time ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Oxygen Vacancy ◽  
Single Crystals ◽  
Room Temperature ◽  
Interfacial Polarization ◽  
Absorption Peak ◽  
Single Relaxation Time

The variation of the dielectric constant (ε′) and the dielectric loss (ε″) have been studied as a function of frequency (102 to 1010 c.p.s.) for normal (as grown), reduced (heated in vacuum), and specially reduced (heated in vacuum in presence of an asymmetric d.c. field) rutile single crystals parallel to c-axis at room temperature. Dispersions in ε′ have been observed in the frequency ranges 102 to 103 and 107 to 109 c.p.s. for all the samples with absorption peaks in ε″ at 2 × 102 and 6 × 107 c.p.s. Also an extra absorption peak in ε″ has been found at 2 × 104 c.p.s. for the specially reduced sample. The absorption peak at 2 × 102 c.p.s. has been observed by many workers and is typical for interfacial polarization. The peak at 6 × 107 c.p.s. appears to be due to a dipole rotation process with a single relaxation time and is identified as due to relaxation of dipoles formed between Ti3+ and a neighboring oxygen vacancy. The possible mechanism of relaxation for the 2 × 104 c.p.s. absorption peak is also discussed.

scholarly journals Complex dielectric behavior of doped polyaniline conducting polymer at microwave frequencies using time domain reflectometry

2019 ◽  
Vol 65 (6 Nov-Dec) ◽  
pp. 590 ◽  
Author(s):  
D.R. Bijwe ◽  
S.S. Yawale ◽  
A.C. Kumbharkhane ◽  
H. Peng ◽  
D.S. Yawale ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Conducting Polymer ◽  
Chemical Oxidation ◽  
Ammonia Solution ◽  
Dielectric Behavior ◽  
Time Domain Reflectometry ◽  
Microwave Frequencies ◽  
Absorbing Property

Nano size Tin Oxide is prepared in the laboratory from SnCl4 and ammonia solution. The polyaniline (PAni) conducting polymer is synthesized by chemical oxidation method using ammonium persulphate as oxidizing agent. The PAni-SnO2 composite was prepared by insitu method. Scanning electron microscopy (SEM) results confirm the particle size of SnO2 in the range of 30-48 nm.   Dielectric  behavior  of  nanocomposite  of  PAni-SnO2 was  studied  in the frequency range 0.01- 20 GHz at -5,0,5,10,15,20 and  25oC. The dielectric constant (real part ε׳) and dielectric loss (imaginary part ε״) have been evaluated. The relaxation time (τ, τo, and τ1) are calculated. The relaxation time was found to be of the order of ps. The dielectric properties of the solids in the form of powders may be useful in understanding the structural behavior of particles in an alternating field. These studies may also be used to formulate models for predicting the dielectric properties. The microwave absorbing property is decided from the dielectric loss of the material. It is observed that the PAni-SnO2 composite can be a good electromagnetic shielding material.

scholarly journals Dielectric loss due to polar molecules in solid paraffin wax

1939 ◽  
Vol 172 (951) ◽  
pp. 502-517 ◽  
Keyword(s):  
Relaxation Time ◽  
Dielectric Loss ◽  
Maximum Rate ◽  
Angular Frequency ◽  
Rate Of Change ◽  
Polar Molecules ◽  
Dielectric Polarization ◽  
Specific Energy Loss ◽  
Maximum Value ◽  
Time Required

According to most theories of dielectric loss the maximum rate of change of dielectric constant and the maximum value of the specific energy loss per unit volume occur at an angular frequency ω (= 2 πv ) which is the inverse of a quantity r known as the relaxation time of the dielectric. The relaxation time is the time required for the polarization of the dielectric to revert to 1/ ϵ of its value after the removal of the applied electric field: and this is a quantity which can be determined experimentally. According to Debye’s theory of polar molecules, part of the dielectric polarization is due to the orientation of the dipoles in line with the applied field and the relaxation time is related closely to the time taken for the molecules to revert to their random positions after removal of the field.

Dielektrische Verluste in verdünnter Lösung und innermolekulare Dipolbeweglichkeit bei Carbinolen / Dielectric Loss of Carbinols in Dilute Solutions and Intramolecular Dipol Orientation

1974 ◽  
Vol 29 (3) ◽  
pp. 440-444
Author(s):  
F. F. Hanna ◽  
A . M. Bishai ◽  
M. Straßmann ◽  
W. Noerpel
Keyword(s):  
Relaxation Time ◽  
Carbon Tetrachloride ◽  
Dielectric Loss ◽  
Benzyl Alcohol ◽  
Phenyl Ring ◽  
Microwave Range ◽  
Dilute Solutions ◽  
Time Constants ◽  
The One ◽  
Angular Oscillations

The dielectric loss of benzyl alcohol, diphenyl- and triphenylcarbinol in dilute solutions of benzene and carbon tetrachloride is measured in the microwave range from 1 to 300 GHz. The absorption curves can be separated into three regions, the one with the longest relaxation time is due to the overall rotation of the molecule. In both the carbinols the OH-group is hindered in its rotation and partly it reorients with time constants which we suggest being due to the rotation of the phenyl ring. For the fast angular oscillations (libration) of the OH-group itself time constants between 0.15 and 3 ps are extrapolated

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