Development of the thermo-conductive electrically insulating epoxy composites using electrospun alumina microfibers

The thermo-conductive electrically insulating epoxy has been pursued for promoting the development of future electronic devices. In this work, the Al
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fibers (AFs) with the diameter of 400∼500 nm and length of several millimeters were fabricated by the electrospinning with sol-gel precursor and followed by calcination. The influence of spinning solution and calcined temperature on the growth of fibers was discussed. Prior to use, the Al
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fibers were functionalized by coupling agent KH-550 (/-AFs), then the epoxy composites with /-AFs were prepared and their microstructure, thermal conductivity and electrical insulating properties were discussed. It was found that /-AFs exhibited uniform dispersion in the matrix and the thermally conductive pathways were well established. With addition of 50 vol% /-AFs, thermal conductivity of the composites was up to ∼1.27 W m
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K
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, and it is more than sixfold larger than that of pure epoxy. Besides, this improvement is accompanied by good dielectric behavior and dielectric breakdown strength compared to that of pure epoxy. The breakdown strength at 63.2% in Weibull-distribution plots of the composites still keep to be 66 kV/mm with addition of 50 wt% fibers.