Filler‐dependent changes in thermal, dielectric, and mechanical properties of epoxy resin nanocomposites

Nagase, Emiri; Iizuka, Tomonori; Tatsumi, Kohei; Hirai, Naoshi; Ohki, Yoshimichi; Yoshida, Seikoh; Umemoto, Takuya; Muto, Hirotaka

doi:10.1002/tee.23264

Cited by 9 publications

(18 citation statements)

References 20 publications

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“…We measured ε r and ε r " in the above-mentioned wide frequency and temperature ranges since broadband frequency data of complex permittivity at different temperatures contain a lot of important information concerning the dielectric behavior of solid dielectrics. We have conducted, in our previous paper [16], such analysis on dielectric behavior of various NCs similar to the present ones, including ones with silica. Therefore, we deal with only the data of ε r and ε r " measured under the industrially important 50 Hz at 20, 100, and 140 • C in this paper.…”

Section: Resultsmentioning

confidence: 93%

“…In other words, some interaction at the large filler-resin interfaces in a NC really alters various properties of the bulk of resin significantly. We have published several papers [8,16,[32][33][34][35][36], which describe examples of experimental results that indicate variations of bulk properties induced by the addition of nanofillers to polymeric insulating materials.…”

Section: Resultsmentioning

confidence: 99%

“…Organic polymers, into which nanofillers (inorganic in most cases and metallic in some cases [1,2]) are dispersed uniformly, are called polymer nanocomposites (NCs) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. They have been attracting much attention in various fields recently since their good potential abilities have been reported.…”

Section: Introductionmentioning

confidence: 99%

“…More specifically, the common goal of the two projects is to develop innovative electrical insulations that can reduce the insulation thickness of the coil windings used in power generators. One of the two projects is for generators up to the 1.5-kVA class [17,18], while the other is for larger generators [13][14][15][16]. For contributing to the project for larger generators, we have been investigating the best nanofiller to add to the epoxy resin.…”

Section: Introductionmentioning

confidence: 99%

“…Up to the present, NCs of epoxy resin with silica (SiO 2 ), rutile (TiO 2 ), magnesia (MgO), or magnesium hydroxide (Mg(OH) 2 ), added as a nanofiller, were selected as candidate materials. Therefore, various characteristics important for electrical insulation, such as impulse breakdown strength [13], insulation lifetime [14], electroluminescence [15], complex permittivity, and elasticity [16], have been investigated in such NCs.…”

Section: Introductionmentioning

confidence: 99%

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Inverse Proportionality of Thermal Conductivity and Complex Permittivity to Filler-Diameter in Epoxy Resin Composites with Silica

et al. 2021

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We prepared six kinds of epoxy resin nanocomposites with silica and an epoxy resin with no silica. The nanocomposites contain silica with different diameters (10, 50, and 100 nm) while their silica contents are 1, 5, 10, and 20 vol%. At 25 and 100 °C, the thermal conductivity has a nearly proportional dependence on the silica content and exhibits an almost reciprocal proportionality to the diameter of the silica. The latter result indicates that the interaction at filler-resin interfaces plays a significant role in heat transfer. However, this view contradicts an easy-to-understand thought that the filler-resin interfaces should work as a barrier for heat transfer. This in turn indicates that the interaction at filler-resin interfaces controls the bulk properties of the resin when the filler is in a nm size. Although the dielectric constant increases with the addition of the silica filler, its increment from the resin with no silica is the smallest in the resin with the 10-nm silica. Therefore, the addition of the 10-nm silica is adequate for electrical insulation purposes.

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Section: Resultsmentioning

confidence: 93%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Inverse Proportionality of Thermal Conductivity and Complex Permittivity to Filler-Diameter in Epoxy Resin Composites with Silica

et al. 2021

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Mechanical and thermal characterization of laminar carbon/epoxy composites modified with magnesium oxide microparticles

Uzay

2021

Polymer Composites

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This paper investigates the effects of magnesium oxide (MgO) microparticles on the mechanical and thermal properties of laminated carbon fiber reinforced polymer composites. The polymer epoxy matrix was modified with 0% (pure), 2 wt%, and 4 wt% MgO fillers. Then the laminar composites were manufactured with the vacuum bag method. The energy absorption capacity and impact strength were determined from the Charpy impact tests, whereas the flexural characteristics were evaluated by conducting three-point bending experiments. Scanned electron microscopy was used to examine both the dispersion of microparticles and the fracture surface of experimentally tested specimens. Thermal performance of the polymer composites with and without MgO additives was analyzed comparatively by performing the thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The decomposition temperatures and glass transition temperatures of the composites were obtained. Approximately 30% increment in impact strength was achieved thanks to the MgO fillers. However, although the flexural strength decreased since the MgO particles caused stress concentration, the flexural modulus was not affected due to the decrease of elongation at break. The TGA and DSC instrumentations showed that the decomposition temperatures increased, and curing behaviors were improved depending upon the MgO content.

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Broadband Complex Permittivity and Electric Modulus Spectra for Dielectric Materials Research

Ohki

2022

IEEJ Transactions Elec Engng

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Measurement of the complex permittivity of a substance in a wide frequency range, for example, from 10 mHz to 100 kHz, provides useful information on the dielectric properties of the substance. In this regard, some of such dielectric properties can be analyzed more clearly if we pay attention to the frequency spectra of electric modulus, which is a reciprocal of complex relative permittivity. Especially, the imaginary part of the electric modulus can be a powerful tool for dielectric materials research. In this paper, this fact is demonstrated clearly by showing abundant examples acquired by the author's laboratory. First, the equations of electric modulus that hold for various dielectric relaxation processes, including their derivation, are shown in an easy-tounderstand manner. After that, for several insulating polymers, actual measurement examples of broadband complex permittivity spectra are shown, up to frequencies of about 100 kHz and a much broader range up to several THz. In the first example of showing permittivity spectra, polyamide exhibits an incredibly high relative permittivity value of 10 6 at high temperatures such as 200 • C at a frequency as low as 10 mHz. This is a result of the phenomenon often called electrode polarization. In other words, if electric charge carriers accumulate in an insulator facing a nearby electrode and have the polarity opposite to that of the electrode, the permittivity of the insulator goes up. In such a case, the dielectric loss factor usually shows a very high value in the low-frequency range and decreases in inverse proportion to the frequency. This reflects the fact that the charge carriers are transported, and the conductivity can be derived from this frequency dependence much more easily with apparently higher reliability than measuring the dc leakage current. Furthermore, it is shown that the coefficient of thermal expansion can be estimated from the permittivity spectra relatively accurately for several polymers that satisfy the necessary condition. Next, taking examples in electric modulus spectra measured in important insulating polymers such as engineering ones, it is demonstrated that the processes of dielectric polarization and relaxation, which are difficult to see in permittivity spectra, can be recognized obviously. Moreover, the effects of the addition of nanosized or microsized fillers to epoxy resin on its thermal property and filler-induced inhomogeneity are analyzed using the electric modulus spectra measured in these samples. The effects of thermal aging treatment and simultaneous aging treatment with heat and radiation on the degradation of cross-linked polyethylene are also analyzed by paying attention to the frequency spectra of its imaginary electric modulus.

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Filler‐dependent changes in thermal, dielectric, and mechanical properties of epoxy resin nanocomposites

Cited by 9 publications

References 20 publications

Inverse Proportionality of Thermal Conductivity and Complex Permittivity to Filler-Diameter in Epoxy Resin Composites with Silica

Inverse Proportionality of Thermal Conductivity and Complex Permittivity to Filler-Diameter in Epoxy Resin Composites with Silica

Mechanical and thermal characterization of laminar carbon/epoxy composites modified with magnesium oxide microparticles

Broadband Complex Permittivity and Electric Modulus Spectra for Dielectric Materials Research

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