Improving the thermal conductivity of PEEK composites with PEI-assisted dispersion of carbon-based fillers

Polyetheretherketone (PEEK) is a semi-crystalline engineering plastic renowned for its exceptional mechanical properties and remarkable corrosion resistance. However, PEEK exhibits poor thermal conductivity, which constrains its applicability in electronic and electrical domains. Herein, in order to improve the thermal conductivity of PEEK, carbon fiber (CF), multi-walled carbon nanotubes (CNT) and boron nitride (BN) were used as thermally conductive fillers to blend with PEEK to improve its thermal conductivity. Since the processing fluidity of fillers in PEEK deteriorates after dispersion, making it difficult to form a thermal conductive network, the thermally conductive fillers were first blended with polyetherimide (PEI) which had good processing fluidity and was compatible with PEEK to make a highly filled thermal conductive masterbatch. The thermal conductive masterbatch was then melt-blended with PEEK to selectively disperse the thermally conductive filler in the PEI phase to form a thermal conductive network. Finally, a PEEK composite material was obtained by compression molding, and its vertical thermal conductivity was increased from 0.25 W/(m·K) to 0.334 W/(m·K). Its tensile strength increased by approximately 26.7% to 123.02 MPa, elastic modulus improved by 135.4% to 1911.46 MPa, and thermal decomposition temperature remained stable around 530°C. The composite material maintains good mechanical properties, thermal stability, and heat resistance. This approach offers a more practical and scalable solution for improving the thermal conductivity of special engineering plastics.