INFLUENCE OF SHEAR ON THE DIELECTRIC CONSTANT OF LIQUIDS

1951 ◽  
Vol 29 (10) ◽  
pp. 848-856 ◽  
Author(s):  
B. L. Funt ◽  
S. G. Mason
Keyword(s):  
Dielectric Constant ◽  
Liquid Crystals ◽  
Carbon Black ◽  
Electric Field ◽  
Velocity Gradient ◽  
Ethyl Cellulose ◽  
Experimental Results ◽  
Particle Orientation ◽  
Nonpolar Solvents ◽  
Polar Polymers

The effects of a velocity gradient upon the dielectric constant were studied in solutions of macromolecules, in suspensions and in liquid crystals. Decreases in dielectric constant under shear were observed for polar polymers in polar and nonpolar solvents. For solutions of ethyl cellulose an increase in dielectric constant was obtained. Nonpolar polymers showed no changes of dielectric constant under shear. Large changes in dielectric constant at low rates of shear were observed in carbon black suspensions. The experimental results are discussed on the basis of particle orientation in a velocity gradient and in an electric field.

scholarly journals Charge Injection Characteristics of Semi-Conductive Composites with Carbon Black-Polymer for HVDC Cable

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1134 ◽  
Author(s):  
Yanhui Wei ◽  
Mingyue Liu ◽  
Wang Han ◽  
Guochang Li ◽  
Chuncheng Hao ◽  
...  
Keyword(s):  
Carbon Black ◽  
Electric Field ◽  
Bottom Electrode ◽  
Charge Injection ◽  
Experimental Results ◽  
Uniform Electric Field ◽  
Insulation Material ◽  
Electrode Structure ◽  
Depolarization Current ◽  
Conductive Composites

Semi-conductive composites composed of carbon black-polymer play an important role in uniform electric field in high voltage direct current (HVDC) cable. They also affect space charge behaviors in the insulation material. However, the charge injection characteristics of semi-conductive composites are not detailed. In this work, the electrode structure of ‘Semi-conductive composites- Insulation material- Metal bottom’ (S-I-M) is proposed, and the currents formed by injected charges from semi-conductive composites are characterized by the thermally stimulated depolarization current (TSDC) method. Further, the experimental results based on the structure of S-I-M are compared with the traditional electrode structure of M-I-M (Metal upper electrode- Insulation material- Metal bottom electrode) and the simplified cable electrode structure of MS-I-M (Metal upper electrode-Semi-conductive electrode- Insulation material- Metal bottom electrode), respectively. The experimental results show that the semi-conductive composite plays an important role in the charge injection process and it presents a different tendency under different compound modes of temperature and electric field. For the low electric field (E ≤ 5 kV/mm) and the low temperature (T ≤ 50 °C), the current caused by the accumulated charges follows the rule, IS > IMS > IM. For the low electric field and high temperature (T > 50 °C), the current caused by the injected charges follows the rule, IMS > IM > IS. This phenomenon is closely related to the interface characterization and contact barrier.

Electrostriction of Natural Rubber Latex/Carbon Black Nanocomposites

2013 ◽  
Vol 844 ◽  
pp. 259-262 ◽  
Author(s):  
Darika Jaaoh ◽  
Chatchai Putson ◽  
Nantakan Muensit
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
Carbon Black ◽  
Electric Field ◽  
Natural Rubber ◽  
Natural Rubber Latex ◽  
Low Frequency ◽  
Young Modulus ◽  
Filler Concentration ◽  
High Productivity

The purpose of this paper is to investigate an electrostrictive behavior of natural rubber (NR) and NR composites filled with carbon black (CB) nanopowders below percolation threshold. These NR elastomers present advantageous features such as a high productivity, elasticity, and ease of processing. In addition, such materials also exhibit the high induced strain and low young modulus for electrostrictive materials that can be used as actuators and energy harvesting. The NR and all composites were prepared by using solution casting method. The electrostrictive property of the composites was evaluated at low electric field (E 5 MV/m) by measuring the electric field induced strain Sz with the photonic displacement apparatus. The surface morphology of the samples was observed by the atomic force microscopy (AFM) and their electrical properties were analyzed as function of concentration and frequency in a range of 102105 Hz. The results show that the dielectric constant and the dielectric loss decrease when the frequency was increased. Moreover, the dielectric constant and the electrical conductivity strongly increase with increasing the CB contents, relate to interfacial charge distribution. While the dielectric loss slightly increases with increasing filler concentration. The electrostriction coefficient tended to increase with a higher CB loading. In comparison at CB 1 wt%, it was found that the electrostriction coefficient of NR composites is approximately 7 times larger than the pure NR. The NR nanocomposites thus seem to be very attractive for low frequency electromechanical applications.

scholarly journals Electrically driven formation and dynamics of Pac-Man solitons in smectic A liquid crystals

2021 ◽  
Author(s):  
Yuan Shen ◽  
Ingo Dierking
Keyword(s):  
Liquid Crystals ◽  
Electric Field ◽  
Spatiotemporal Chaos ◽  
Practical Applications ◽  
Smectic A ◽  
Fundamental Science ◽  
Smectic A Liquid Crystals

Electric field driven instabilities of liquid crystals, such as electro-convections, spatiotemporal chaos, backflows, and solitons are of great importance for both fundamental science and practical applications. Here we demonstrate that...

Light scattering by liquid crystals in an electric field

1976 ◽  
Vol 33 (2) ◽  
pp. 773-781
Author(s):  
N. L. Kramarenko ◽  
I. V. Kurnosov ◽  
Yu. V. Naboikin
Keyword(s):  
Liquid Crystals ◽  
Light Scattering ◽  
Electric Field
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