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Electrical Insulation (electrical + insulation)

Distribution by Scientific Domains

Polymers and Materials Science	80%

Selected Abstracts

Some biophysical properties of castor oil esterified with some acid anhydrides

EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 10 2008
Mona A. Saied
Abstract A series of castor oil adducts were synthesized by esterification of castor oil with acid anhydrides: phthalic, maleic and succinic anhydrides. The chemical structure of castor oil and the prepared adducts were characterized by means of IR and 1H,NMR spectroscopy. The number-average and weight-average molecular weights were measured by gel permeation chromatography. The electrical properties were studied through the permittivity, dielectric loss and conductivity measurements, which are considered to be in the range of electrical insulation. The electrical conductivity, which describes the ionic mobility of the systems, was found to be in the range of 10,9 to 10,12,S/cm. This indicates that castor oil and its esters could be used for antistatic applications. The viscosity,, and the activation energy,E,, obtained from the dependency of viscosity on temperature using the Arrhenius equation, were found to increase with increasing molecular weight of the system. The effect of different concentrations of castor oil and its esters on the growth activities of the sugar beet pathogens R.,solani and S.,rolfsii was studied through the determination of percent germination, average length of hyphal extensions, dry mass yield and the production of sclerotia. The obtained data indicate that the esterification of castor oil with anhydrides improves the antifungal activity. [source]

Towards Thermoconductive, Electrically Insulating Polymeric Composites with Boron Nitride Nanotubes as Fillers

ADVANCED FUNCTIONAL MATERIALS, Issue 12 2009
Chunyi Zhi
Abstract Ultilizing boron nitride nanotubes (BNNTs) as fillers, composites are fabricated with poly(methyl methacrylate), polystyrene, poly(vinyl butyral), or poly(ethylene vinyl alcohol) as the matrix and their thermal, electrical, and mechanical properties are evaluated. More than 20-fold thermal conductivity improvement in BNNT-containing polymers is obtained, and such composites maintain good electrical insulation. The coefficient of thermal expansion (CTE) of the BNNT-loaded polymers is dramatically reduced because of interactions between the polymer chains and the nanotubes. Moreover, the composites possess good mechanical properties, as revealed by Vickers microhardness tests. This detailed study indicates that BNNTs are very promising nanofillers for polymeric composites, allowing the simultaneous achievement of high thermal conductivity, low CTE, and high electrical resistance, as required for novel and efficient heat-releasing materials. [source]

Morphology and thermal and dielectric behavior of cycloaliphatic epoxy/trimethacrylate interpenetrating polymer networks for vacuum-pressure-impregnation electrical insulation

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008
Jingkuan Duan
Abstract Vacuum pressure impregnation has been known as the most advanced impregnation technology that has ever been developed for large and medium high-voltage electric machines and apparatuses. We developed one new type of vacuum-pressure-impregnation resin with excellent properties by means of a novel approach based on in situ sequential interpenetrating polymer networks resulting from the curing of trimethacrylate monomer [trimethylol-1,1,1-propane trimethacrylate (TMPTMA)] and cycloaliphatic epoxy resin (CER). In this study, the influence of the concentrations of the components and their microstructures on their thermal and dielectric behaviors were investigated for the cured CER/TMPTMA systems via atomic force microscopy, dynamic mechanical analysis, thermogravimetric analysis, and dielectric analysis. The investigation results show that the addition of TMPTMA to the CER,anhydride system resulted in the formation of a uniform and compact microstructure in the cured epoxy system. This led the cured CER/TMPTMA systems to show much higher moduli in comparison with the pure CER,anhydride system. The thermogravimetric analysis results show that there existed a decreasing tendency in the maximum thermal decomposition rates of the cured CER/TMPTMA systems, which implies that the thermal stability properties improved to some extent. The dielectric analysis results show that the cured CER/TMPTMA systems displayed quite different dielectric behaviors in the wide frequency range 0.01 Hz,1 MHz and in the wide temperature range 27,250°C compared with the cured CER,anhydride system. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Synthesis of alkyd resin from jatropha and rapeseed oils and their applications in electrical insulation

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2008
V. C. Patel
Abstract Alkyd resin based on jatropha and rapeseed oils using glycerol, phthalic, and maleic anhydride were synthesized to obtain the resins suitable for electrical applications. These resins were characterized for the physical and electrical properties. Varnishes were prepared using these resins and characterized as per standard methods. In general, both the varnishes prepared from alkyd resin from jatropha and rapeseed oils meet the standard requirements. However, the varnish prepared from rapeseed oil was found to be superior in terms of adhesion, break down voltage, and volume resistivity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

New type of phenolic resin,The curing reaction of bisphenol A based benzoxazine with bisoxazoline and the properties of the cured resin.

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008

Abstract The curing reaction of a bisphenol A based benzoxazine [2,2-bis(3,4-dihydro-3-phenyl-1,3-benzoxazine) propane (Ba)] and bisoxazoline with a latent curing agent and the properties of the cured resins were investigated. With a latent curing agent, the ring-opening reaction of the benzoxazine ring occurred more rapidly, and then the phenolic hydroxyl group generated by the ring-opening reaction of the benzoxazine ring also reacted with the oxazoline ring more rapidly. The cure time of molten resins from Ba and bisoxazoline with a latent curing agent was reduced, and the cure temperature was lowered, in comparison with those of resins from Ba and bisoxazoline without a latent curing agent. The melt viscosity of molten resins from Ba and bisoxazoline with a latent curing agent was kept around 50 Pa s at 80°C even after 30 min, and molten resins from Ba and bisoxazoline with a latent curing agent showed good thermal stability below 80°C. However, above 170°C, the curing reaction of Ba with bisoxazoline with a latent curing agent proceeded rapidly. Cured resins from Ba and bisoxazoline with a latent curing agent showed good heat resistance, flame resistance, mechanical properties, and electrical insulation in comparison with cured resins from Ba and bisoxazoline without a latent curing agent. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]