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Dielectric Strength (dielectric + strength)

Distribution by Scientific Domains

Polymers and Materials Science	75%

Selected Abstracts

High Breakdown Field Dielectric Elastomer Actuators Using Encapsulated Polyaniline as High Dielectric Constant Filler

ADVANCED FUNCTIONAL MATERIALS, Issue 19 2010
Martin Molberg
Abstract A novel method allowing rapid production of reliable composites with increased dielectric constant and high dielectric strength for dielectric elastomer actuators (DEA) is reported. The promising approach using composites of conductive particles and insulating polymers generally suffers from low breakdown fields when applied to DEA devices. The present publication shows how to overcome this deficiency by using conductive polyaniline (PANI) particles encapsulated into an insulating polymer shell prior to dispersion. PANI particles are encapsulated using miniemulsion polymerization (MP) of divinylbenzene (DVB). The encapsulation process is scaled up to approximately 20 g particles per batch. The resulting particles are used as high dielectric constant (,,) fillers. Composites in a polydimethylsiloxane (PDMS) matrix are prepared and the resulting films characterized by dielectric spectroscopy and tensile tests, and evaluated in electromechanical actuators. The composite films show a more than threefold increase in ,,, breakdown field strengths above 50 V ,m,1, and increased strain at break. These novel materials allow tuning the actuation strain or stress output and have potential as materials for energy harvesting. [source]

Corrosion control by antioxidant DBPC in insulating oil

IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 3 2009
Takashi Ito Non-member
Abstract In order to evaluate corrosive sulfur in insulating oil quantitatively, wave length dispersive X-ray (WDX) technique has been reported 1. Using this technique, antioxidant 2,6-di- tert -butyl- p -cresol (DBPC) was found to be effective to suppress corrosion caused by dibenzyl disulfide (DBDS). The effect of corrosion prevention continues for a long term when a certain amount of DBPC is added to oil. The durability of DBPC was also evaluated by HPLC. It is possible to add relatively a good deal of DBPC to oil because DBPC has higher solubility than passivator and little effect on dielectric strength. Furthermore, DBPC was used with passivator simultaneously, and corrosion control time was far extended by their synergy effect. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source]

Dielectric Response of Aramid Fiber-Reinforced PEEK

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 16 2002
Nina Korbakov
Abstract Dielectric spectroscopy was applied for the first time to aramid fiber-reinforced PEEK, wherein the effect of the fiber on the dielectric response was examined for both amorphous and crystalline poly(ether ether ketone) (PEEK) over wide temperature and frequency ranges. Whereas the temperature behavior of the dielectric losses of the materials exhibited the typical , and , processes of PEEK, the specific effect of the fibers in the crystalline PEEK was revealed in shifting the , process to a higher temperature. The unique effect of the fibers was expressed by a significantly higher activation energy and lower dielectric strength for the , relaxation, reflecting a higher constraint level that is imposed by the fiber. It is proposed that this additional constraint is associated with fiber generated transcrystallinity. Scanning electron micrograph of transverse fracture surface of crystallized unidirectional aramid fiber-reinforced PEEK. [source]

Synthesis and Electrorheological Characterization of Polyaniline/Barium Titanate Hybrid Suspension

MACROMOLECULAR SYMPOSIA, Issue 1 2006
Fei Fei Fang
Abstract As organic/inorganic composites having attracted much attention due to their heterogeneous physical properties, conducting polyaniline (PANI) and barium titanate (BaTiO3) which possesses large electronic resistance and excellent dielectric strength, were utilized to synthesize PANI/BaTiO3 hybrid which is applicable for an electrorheological (ER) material via ,in-situ' oxidative polymerization. Physical properties of the obtained PANI/BaTiO3 composites were characterized via Fourier-transform infrared spectra (FT-IR), thermogravimetry analysis (TGA), and scanning electron microscopy (SEM). The ER behaviors were investigated via a rotational rheometer, and their shear stresses were fitted using our previously proposed rheological equation of state. [source]