Electrical properties of polymer nanocomposites based upon organophilic layered silicates

Zilg, Carsten; Kaempfer, Dirk; Thomann, Ralf; Muelhaupt, Rolf; Montanari, G

doi:10.1109/ceidp.2003.1254913

Cited by 45 publications

(31 citation statements)

References 13 publications

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“…Electrical properties were measured on flat specimens, 150-200 µm thick, constituted by polymer and 6 wt% nanoclays, obtained through extrusion in a corotation twin-screw extruder at 120 °C for EVA and 210 °C for PP. TEM and WAXS observations (4) (5) indicate that most of the specimen volume of EVA and PP based nanocomposites was filled by exfoliated nanoparticles, while polymer chains did not succeed to penetrate silicate layers in the unmodified Somasif (thus creating, as a matter of fact, clusters of nanograins of micrometric size) (8) (24) .…”

Section: Materials Preparationmentioning

confidence: 99%

“…Their behavior has been investigated through various techniques, such as Transmission Electron Microscopy, TEM, Wide-Angle X-Ray Spectroscopy, WAXS, mechanical strength, conduction current, space charge, partial discharges and voltage breakdown tests (4)- (11) . It has been proved that the dispersion of an inorganic phase in the polymeric matrix may improve voltage endurance (9)- (12) , dielectric strength (4), (12)- (14) , thermal stability (2)(5) (15) and mechanical properties (1) (16) in relation to particle size and arrangement on nanometric scale. Contrasting information can be found in literature regarding to polarization behavior.…”

Section: Introductionmentioning

confidence: 99%

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Polarization Processes of Nanocomposite Silicate-EVA and PP Materials

Montanari

Palmieri

Testa³

et al. 2006

IEEJ Trans. FM

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Recent works indicate that polypropylene (PP) and ethylene-vinylacetate (EVA) filled by nanosilicates may present low content of space charge and high electric strength. It has been proved that the dispersion of an inorganic phase in the polymeric matrix may improve voltage endurance, dielectric strength, thermal stability and mechanical properties in relation to particle size and arrangement on nanometric scale. Two polymeric materials, widely employed as electrical insulation for apparatus involved in energy transport, that is, ethylene vinylacetate (EVA) and isotactic polypropylene (PP) are examined. The nanofiller consists of an organophilic layered silicate (MEE), the purified MEE will be named MEE-w.Dielectric spectroscopy in time and frequency domain constitutes a useful tool for electrical insulation evaluation and diagnosis, and it can contribute to the understanding of electrical behaviour of complex solid polymer systems. In this paper, the results of dielectric spectroscopy analysis in time and frequency domain, for purified and unpurified filler nanocomposites, in a wide temperature range, are presented.Frequency-domain dielectric measurements were performed in order to appreciate the relaxation processes taking place at lower temperatures (-20 to 20 °C) over the 10 2 -10 6 Hz frequency range.The charging-discharging current measurements, through Fourier time to frequency data transformation, gave information about the slowest polarisation processes, that are usually hidden by the conduction current contribution. Space charge measurement data are also considered in order to understand the effect of nanostructuration and purification on charge carriers. While the relaxation process of EVA, α process, associated with glass transition of the material amorphous phase, results unchanged from base to nanostructured material (i.e., the nanofiller particles do not affect the chain mobility of the polymer), nanocomposites EVA and PP have shown the rise of a new process at higher temperatures respect to the typical host material processes, as well as a different distribution of relaxation processes. In Fig. 1, that displays the imaginary permittivity of EVA+MEE-w nanocomposite, the loss peaks, due to the α and α' process, can be clearly seen. The α' process can be ascribed to the interaction between the polymer matrix and MEE nanolayers.The temperature location of the process, which approaches the melting region of EVA, and its absence in the pure polymer let us argue that the α' relaxation process can be ascribed to a charge polarization of the Maxwell-Wagner-Sillars type, which is due likely to charge trapping at the interfaces between the nanofiller particles and the polymer. All the presented relaxation processes are thermally-activated and their activation energies, reported in Table 1, were estimated reporting the loss peak frequency and temperature of the isothermal measurements in the Arrhenius plot.The EVA nanocomposite obtained by an unpurified filler has shown a huge increment of real and imaginary...

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Section: Materials Preparationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Polarization Processes of Nanocomposite Silicate-EVA and PP Materials

Montanari

Palmieri

Testa³

et al. 2006

IEEJ Trans. FM

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“…Ratio k 2 in dc BD versus nano/micro-filler loading, (■ from [57][58][59][60][61][62], all nanofillers in these papers were treated; • from [57][58][59][60][61]. ) [57] dc BD tests were performed with a ramp rate of 500 V/s.…”

Section: Figurementioning

confidence: 99%

“…The thickness was about 200 μm. [62] dc strength measurements were carried out in mineral oil at 20 o C with a ramp rate of 5 kV/s. The thickness of specimens was about 400 μm.…”

Section: Figurementioning

confidence: 99%

Short-term breakdown and long-term failure in nanodielectrics: a review

Yin

Chen

et al. 2010

IEEE Trans. Dielect. Electr. Insul.

299

172

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Nanodielectrics, which are concentrated in polymer matrix incorporating nanofillers, have received considerable attention due to their potential benefits as dielectrics. In this paper, short-term breakdown and long-term failure properties of nanodielectrics have been reviewed. The characteristics of polymer matrix, types of nanoparticle and its content, and waveforms of the applied voltage are fully evaluated. In order to effectively comment on the published experimental data, a ratio k has been proposed to compare the electric properties of the nanodielectrics with the matrix and assess the effect for nanoparticles doping. There is evidence that the short-term breakdown properties of nanodielectrics show a strong dependence on the applied voltage waveforms. The polarity and the cohesive energy density (CED) of polymer matrix have a dramatic influence on the properties of nanodielectrics. Nanoparticle doped composites show a positive effect on the long-term failure properties, such as ageing resistance and partial discharge (PD) properties of nanocomposites are superior than microcomposites and the matrix. The larger the dielectric constant and CED of the matrix become, the more significant improvements in long-term performance appear. Based on the reported experimental results, we also present our understandings and propose some suggestions for further work.

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“…To improve the brittleness, "repaired" PET is modified with an epoxy group containing styrene thermoplastic elastomer and polycaprolactone (Sikdar et al, 2006). To obtain the side material for cooling towers, "repaired" PET is modified with styrenic thermoplastic elastomer ( Arif et al, 2007;Zilg et al, 1998;). Nanocomposites ca be achieved with nonmodified natural montmorillonite or with ion-exchanged clay modified with quaternary ammonium salt (Pegoretti et al,2004;Lee & Lichtenhan, 1999;Sharma, 1999;Schmidt et al, 1999;Carotenuto et al, 2000;Aravind, 2007;Bandosz,1996;Bartholome, 2005;Buxton, 2002;Chrissopoulou, 2005;Feng, 2002;Utraki & Kamal, 2002).…”

Section: Compounds Composites and Nanocomposites Realised By Physicamentioning

confidence: 99%