Abstract
Polymer composites, with both high thermal conductivity and high electrical insulation strength, are desirable for power equipment and electronic devices, to sustain increasingly high power density and heat flux. However, conventional methods to synthesize polymer composites with high thermal conductivity often degrade their insulation strength, or cause a significant increase in dielectric properties. In this work, we demonstrate epoxy nanocomposites embedded with silver nanoparticles (AgNPs), and modified boron nitride nanosheets (BNNSs), which have high thermal conductivity, high insulation strength, low permittivity, and low dielectric loss. Compared with neat epoxy, the composite with 25 vol% of binary nanofillers has a significant enhancement (~10x) in thermal conductivity, which is twice of that filled with BNNSs only (~5x), owing to the continuous heat transfer path among BNNSs enabled by AgNPs. An increase in the breakdown voltage is observed, which is attributed to BNNSs-restricted formation of AgNPs conducting channels that result in a lengthening of the breakdown path. Moreover, the effects of nanofillers on dielectric properties, and thermal simulated current of nanocomposites, are discussed.
Highlights
Miniaturization of power equipment and electronic devices, coupled with a high voltage electromagnetic environment, demands superior thermal conductivity and electrical insulation strength in insulating materials [1,2,3]
There exists diffraction peaks at 2θ ≈ 26.76◦, 41.58◦, 43.78◦, 50.05◦, 55.02◦, 71.31◦, and 75.86◦ for both boron nitride nanosheets (BNNSs) and AgNPs-BNNSs, which correspond to the crystal planes (002), (100), (101), (102), (004), (104), and (110) of Hexagonal boron nitride (h-BN), respectively [30,31]
We successfully achieved nanocomposites with high thermal conductivity, high insulation strength, low permittivity, and low dielectric simultaneously in EP-AgBN, solving the problem that polymer composites with high thermal conductivity always have low insulation strength or high dielectric parameters
Summary
Miniaturization of power equipment and electronic devices, coupled with a high voltage electromagnetic environment, demands superior thermal conductivity and electrical insulation strength in insulating materials [1,2,3]. An ideal insulating material is expected to possess high thermal conductivity, high breakdown strength, low permittivity, and low dielectric loss, simultaneously [4]. Polymers are widely used as insulating materials for their excellent electrical insulation properties [5,6], but their low thermal conductivity (~0.2 W m−1 K−1 at room temperature) reduces the lifetime and reliability of power equipment and electronic devices [7,8,9]. By placing AgNPs on the surface of BNNSs, and adding the hybrid nanofiller into the epoxy matrix, we successfully synthesized an epoxy nanocomposite (EP-AgBN) with superb thermal conductivity, high insulation strength, low permittivity, and low dielectric loss. It is expected that the EP-AgBN exhibits strong potential as an insulating material for power equipment and electronic devices, such as insulators, flexible substrates, and electronic packages
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