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Abstract: A kind of polymer composite was fabricated using polystyrene as the matrix and Si3N4 powder as filler employing the method of heat press molding. Microstructure, thermal conductivity and dielectric constant of the Si3N4 filled composite were evaluated. The effect of the volume fraction of Si3N4, the particle size of the polystyrene matrix and the silane treatment of Si3N4 filler on the thermal conductivity of the composite was investigated; dielectric constant of the composite was evaluated. The main factors that affect the thermal conductivity of the composite were confirmed through theoretical analyzing of the experimental data and the thermal conductivity model. Experimental results show that with the filler content increasing, a thermally conductive network is formed in the composites, thus the thermal conductivity of the composite increases rapidly. The composites experience a highest thermal conductivity of 3.0W/mK when the volume fraction of the filler reaches 40%. The increasing of thermal conductivity is dominated by the ease of forming a thermal conductive network. A larger polystyrene particle size, a higher Si3N4 filler content and the silane treatment of the filler have a beneficial effect on improving the thermal conductivity. The dielectric constant increases with the content of Si3N4 filler, however, it remains at a relatively low lever (<4, at 1MHz). [Copyright &y& Elsevier]

For new-generation miniaturized and high-frequency electronics, it is of vital importance to develop advanced electronic packaging materials, which combine high electromagnetic interference (EMI) shielding effectiveness (SE) and efficient thermal management capabilities, including heat absorption, thermal conductivity (TC) and heat dissipation. However, high EMI SE and efficient thermal management usually cannot complement each other for the same packaging material, because EMI shielding devices convert electromagnetic radiation directly into heat consumption, leading to consequent severe challenge to dispose heat dissipation. Herein, we have newly developed a high-performance phase change composites, in which MXene is confined in shape-stabilized phase change material (PCM) for simultaneous achievement of high EMI SE and efficient thermal management. Regarding high EMI, MXene can effectively shield electromagnetic radiation by converting the radiation into heat consumption. As for thermal management, PCM enables efficient heat absorption via the phase change process, and MXene enhances the thermal conductivity (TC) of MXene/PCM composite to facilitate heat dissipation. As a result, our developed MXene/PCM composite can achieve a high EMI SE of 64.7 dB in X-band, with an improved TC of 0.74 W/m·K. Furthermore, the interlayer capillary effect of MXene inhibits the leakage of liquid PCM during the solid-liquid phase transition, which can maintain the PCM shape stability. Our newly-designed shape-stabilized MXene/PCM composites with high EMI SE and large TC shed new light on designing EMI shielding materials with prolonged exposure to electromagnetic radiation, which can be envisioned to exhibit vast implications for advanced new-generation miniaturized and high-frequency electronics. [Display omitted] [ABSTRACT FROM AUTHOR]