Morphology and interfacial control of micron-scale copper for thermally conductive thermoplastic composites

Achieving efficient thermal transport in thermoplastics without compromising other essential properties remains a major challenge for advanced thermal management. Conventional strategies often rely on nanofillers or complex hybrid systems that are difficult to disperse uniformly and lack industrial scalability. This study addresses this limitation by (i) developing thermally conductive polycarbonate (PC)-based composites filled with micron-sized copper powders through melt compounding and (ii) investigating the effects of filler morphology and surface modification on composite performance. Surface modification with 3-mercaptopropyltriethoxysilane (MPTES) introduces a dual anchoring mechanism through Cu–S bonding and silane condensation, markedly improving filler dispersion and interfacial compatibility, particularly for dendritic copper. The transient plane source (TPS) measurement reveals that at 11.8 vol% loading, the modified dendritic composite (PC/md-Cu) achieves a thermal conductivity of 0.43 W m −1 K −1 — about 32 % higher than the unmodified counterpart — while maintaining a volume resistivity of ∼10 14 Ω cm for electrically insulating thermal management, with tensile strength of 72.5 MPa (26.7 % above neat PC). The findings demonstrate that the interplay between dendritic filler structure and silane-mediated interfacial regulation governs thermal transport behavior, offering a practical route toward the development of thermally conductive yet electrically insulating thermoplastic composites by screw extrusion and injection molding.