Influence of alumina content and thermal treatment on the thermal conductivity of UPE/Al<sub>2</sub>O<sub>3</sub> composite

Wu, Xinfeng; Jiang, Pingkai; Zhou, Yun; Yu, Jinhong; Zhang, Fuhua; Dong, Lihua; Yin, Yansheng

doi:10.1002/app.40528

Cited by 43 publications

(19 citation statements)

References 34 publications

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“…Although the electrical conductivity of metallic fillers could be somewhat tailored by oxidation or surface treatment [80,81], the high thermally conductive ceramic fillers is more preferable for not only their electrical insulation property but also thermal stabilities. Typical high thermal conductivity ceramic nano-fillers are magnesium oxide (MgO) [82][83][84], aluminum oxide (Al2O3) [85][86][87][88], silicon nitride (Si3N4) [89][90][91], silicon carbide (SiC) [92][93][94], zinc oxide (ZnO) 21 [95], aluminum nitride (AlN) [96][97][98][99], and boron nitride (BN) [100][101][102][103][104]. Compared with the metallic and ceramic fillers, nanostructured carbon fillers have attracted more intensive interests because of their high thermal conductivity.…”

Section: Thermal Conductivity Of Polymer Nanocompositesmentioning

confidence: 99%

Thermal conductivity of polymers and polymer nanocomposites

Huang

Qian

Yang

2018

Materials Science and Engineering: R: Reports

648

391

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Polymers are widely used in industry and in our daily life because of their diverse functionality, light weight, low cost and excellent chemical stability. However, on some applications such as heat exchangers and electronic packaging, the low thermal conductivity of polymers is one of the major technological barriers. Enhancing the thermal conductivity of polymers is important for these applications and has become a very active research topic over the past two decades. In this review article, we aim to: 1). systematically summarize the molecular level understanding on the thermal transport mechanisms in polymers in terms of polymer morphology, chain structure and inter-chain coupling; 2). highlight the rationales in the recent efforts in enhancing the thermal conductivity of nanostructured polymers and polymer nanocomposites. Finally, we outline the main advances, challenges and outlooks for highly thermal-conductive polymer and polymer nanocomposites. the inter-chain coupling. Fig. 1 Schematic diagrams of a polymer: (a) the morphology of a polymer consisting of crystalline and amorphous domains; (b) structure of a polymer chain.In addition to engineering the morphology of polymer chains, another common method to enhance the thermal conductivity of polymers is to blend polymers with highly thermal conductive fillers. The progress of nanotechnology over the last two decades not only provides more diverse high thermal conductivity fillers of different material types and topological shapes but also advances the understanding at the nanoscale. Fig. 2 shows a sketch of a polymer nanocomposite to illustrate the thermal transport mechanisms. In general, there are two types of polymer nanocomposites depending on whether nano-fillers form a network or not. When the filler concentration is low, no inter-filler networks could be formed, as shown in Fig. 2(a). The thermal conductivity is essentially determined by the filler-matrix coupling, i.e, interfacial thermal resistance, and the concentration and the geometric shapes of fillers. When the filler concentration is large enough, high conductivity fillers might form thermally conductive networks, as shown in Fig. 2(b). Although nanocomposites with filler network could possess a higher thermal conductivity than that without a network, their thermal conductivity could still be low due to the large inter-filler thermal contact resistance. Recently, three-dimensional fillers, such as carbon and graphene foams, have drawn a lot of attention. The fundamental thermal transport mechanisms and recent synthesis efforts in both types of nanocomposites are reviewed.This review article is organized as follows. In Section 2, we introduce the experimental progress on the enhancement of thermal conductivity by aligning polymer chains, and then review the methods to further tune the thermal conductivity by engineering chain structure and inter-chain coupling, as illustrated in Fig. 3(a). In Section 3, we discuss the thermal conductivity of polymer nanocomposites both with and without inter...

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Section: Thermal Conductivity Of Polymer Nanocompositesmentioning

confidence: 99%

Thermal conductivity of polymers and polymer nanocomposites

Huang

Qian

Yang

2018

Materials Science and Engineering: R: Reports

648

391

View full text Add to dashboard Cite

show abstract

“…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: 97%

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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“…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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Influence of alumina content and thermal treatment on the thermal conductivity of UPE/Al₂O₃ composite

Cited by 43 publications

References 34 publications

Thermal conductivity of polymers and polymer nanocomposites

Thermal conductivity of polymers and polymer nanocomposites

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

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

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Influence of alumina content and thermal treatment on the thermal conductivity of UPE/Al2O3 composite

Cited by 43 publications

References 34 publications

Thermal conductivity of polymers and polymer nanocomposites

Thermal conductivity of polymers and polymer nanocomposites

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

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

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Influence of alumina content and thermal treatment on the thermal conductivity of UPE/Al₂O₃ composite