Thermal conductivity of epoxy composites with a binary-particle system of aluminum oxide and aluminum nitride fillers

Choi, Seran; Kim, Jooheon

doi:10.1016/j.compositesb.2013.03.002

Cited by 289 publications

(153 citation statements)

References 17 publications

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“…Similarly, increases in AC breakdown strength in epoxy/alumina systems have been reported [16,17] while, in another study [18], absorbed water was reported to reduce the electrical breakdown strength of a series of alumina/ethylene-co-butene acrylate composites. Other notable papers on alumina [19,20] and aluminum nitride [21,22] focus on their improved thermal conductivity, which could potentially increase short term overload ratings if such composites were to be employed in a high voltage cable system [23]. In all these studies, two key variables are thought to be important in determining breakdown performance -particle dispersion and water absorption.…”

Section: Introductionmentioning

confidence: 99%

The effects of hydration on the DC breakdown strength of polyethylene composites employing oxide and nitride fillers

Hosier

Praeger

Vaughan

et al. 2017

IEEE Trans. Dielect. Electr. Insul.

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Particle dispersion, water absorption/desorption and electrical breakdown behavior were studied in a range of polyethylene composites having a common matrix morphology. Three different conditioning routes (dry, ambient and wet) were used to vary the absorbed water content. Systems employing oxide fillers (silica and alumina) were found to have poor or intermediate levels of particle dispersion and could absorb/desorb significant amounts of water. Consequently, they required drying to provide breakdown strengths comparable to that of the host matrix. Systems based on calcined silica exhibited reduced water absorption and provided improved breakdown strength after ambient conditioning, despite having an identical dispersion to those utilizing untreated silica. Composites employing nitride fillers (silicon nitride and aluminum nitride) were found to have good or intermediate levels of particle dispersion. These absorbed far less water and hence provided breakdown strength values comparable to that of the host matrix following ambient conditioning. Their breakdown strength was degraded after wet conditioning with both exhibiting similar breakdown strengths despite there being a large difference in the level of particle dispersion between the two fillers. In composites based upon a hydrophobic host matrix, water absorption is largely determined by particle surface chemistry and, although the above results are presented in terms of water absorption, we suggest that changes in this characteristic can be interpreted as a proxy for changed surface chemistry. The results suggest that surface chemistry is at least as important as particle dispersion in determining the electrical breakdown strength.

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Section: Introductionmentioning

confidence: 99%

The effects of hydration on the DC breakdown strength of polyethylene composites employing oxide and nitride fillers

Hosier

Praeger

Vaughan

et al. 2017

IEEE Trans. Dielect. Electr. Insul.

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“…In a second publication by the same authors [23], the effect of water conditioning was investigated in detail and, here, it was found that the electrical conductivity of the nanocomposites was higher than that of the unfilled reference material, particularly following storage under wet conditions. Improved thermal conductivity has been reported extensively for relatively high filler loadings (>10 %) for alumina dispersed within various host polymers [24][25][26], which could be advantageous in a technological application such as high voltage cables, permitting heat from the conductor core to be extracted more readily, so increasing ratings [27]. However many studies indicate that such high filler loadings are detrimental to dielectric properties [14,16,17,28,29] such that, in practice, a trade-off between thermal conductivity and dielectric properties may be required.…”

Section: Introductionmentioning

confidence: 99%

The Effects of Water on the Dielectric Properties of Aluminum-Based Nanocomposites

Hosier¹,

Praeger²,

Vaughan

et al. 2017

IEEE Trans. Nanotechnology

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Abstract-A series of polyethylene nanocomposites was prepared utilizing aluminum nitride or alumina nano-powders with comparable morphologies. These were subsequently subjected to different conditioning regimes, namely prolonged storage in vacuum, the ambient laboratory environment or in water. The effect of filler loading and conditioning (i.e. water content) on their morphological and dielectric properties was then examined. Measurements indicated that, in the case of aluminum nitride nanocomposites, none of the conditioning regimes led to significant absorption of water and, as such, neither the dielectric properties nor the DC conductivity varied. Conversely, the alumina nanocomposites were prone to the absorption of an appreciable mass of water, which resulted in them displaying a broad dielectric relaxation, which shifted to higher frequencies, and a higher DC electrical conductivity. We ascribe these different effects to the interfacial surface chemistry present in each system and, in particular, the propensity for hydrogen bonding with water molecules diffusing through the host matrix. Technologically, the use of nanocomposites based upon systems such as aluminum nitride, in place of the commonly used metal oxides (alumina, silica, etc.), eliminates variations in dielectric properties due to absorption of environmental water without resorting to the adoption of techniques such as surface functionalization or calcination in an attempt to render nanoparticle surface chemistry hydrophobic.

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“…Alumina nanofiber mats were impregnated with the mixture and were placed under vacuum and cured at 120°C. The alumina content (vol%) in the sheet was calculated by using the density of alumina, 3.965 g/cm 3 [8].…”

Section: Formation Of Polyurethane Sheets Containing Alumina Nanofibersmentioning

confidence: 99%

“…They reported that the surface modification of BN increases the thermal conductivity of the composites (4.11 W/mK at 70 wt% of modified BN particle) [7]. Choi and Kim investigated the thermal conductivity of the epoxy composites with a binary particle of alumina and AN [8]. The thermal conductivity of a composite having large-sized AN (10 μm) and smallsized alumina (0.5 μm) particles was found to be 3.402 W/mK at 58.4 vol% total filler content.…”

Section: Introductionmentioning

confidence: 99%

Thermal Conductivity of Polyurethane Sheets Containing Alumina Nanofibers

et al. 2015

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Thermal conductivity of epoxy composites with a binary-particle system of aluminum oxide and aluminum nitride fillers

Cited by 289 publications

References 17 publications

The effects of hydration on the DC breakdown strength of polyethylene composites employing oxide and nitride fillers

The effects of hydration on the DC breakdown strength of polyethylene composites employing oxide and nitride fillers

The Effects of Water on the Dielectric Properties of Aluminum-Based Nanocomposites

Thermal Conductivity of Polyurethane Sheets Containing Alumina Nanofibers

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