Synergistic improvement of thermal conductivities of polyphenylene sulfide composites filled with boron nitride hybrid fillers

Hybrid fillers of micrometer boron nitride/nanometer boron nitride (mBN/nBN) were employed to fabricate the highly thermally conductive insulating mBN/nBN/polyphenylene sulfide ((mBN/nBN)/PPS) composites via mechanical ball-milling followed by hot-compression method. The thermally conductive coefficient (λ), dielectric constant (ε) & dielectric loss tangent (tan δ) values and thermal stabilities were all enhanced with the increasing addition of mBN/nBN hybrid fillers. The λ value was improved from 0.286 W/mK for pristine PPS matrix to 2.638 W/mK for the (mBN/nBN)/PPS composite with 60 wt% mBN/nBN (mass fraction, 2:1) hybrid fillers. Appropriate addition of the mBN/nBN hybrid fillers played a role of heterogeneous nucleation for PPS matrix. Agari model fitting revealed that the mBN/nBN hybrid fillers could be much easier to form the continuous thermally conductive channels & networks. The corresponding ε and tan δ values still maintained relatively lower level of 3.96 and 0.022, respectively. And the corresponding THeat-resistance index (THRI) value was beyond 277.8 °C.