Effect of h-BN and aluminosilicate filler configuration and distribution on thermal conductivity and structural integrity of hybrid PEEK composites

Official URL: https://dx.doi.org/10.1002/pc.70137

Achieving high through-plane thermal conductivity (TC) and mechanical strength in PEEK-based composites at high filler loadings is limited by processing challenges, poor filler-matrix interfaces, and filler aggregation. This work addresses these issues by using a hybrid filler approach using hexagonal boron nitride (hBN) and aluminosilicate (AlS) fillers in a PEEK matrix via an optimized twin-screw co-extrusion. During processing, controlled melt flow facilitated the polymer-assisted filler separation, preserving hBN's platelet form and enabling a synergistic hybrid effect at a combined 60 wt% loading. Results show that composites with higher hBN content exhibited greatly enhanced TC, with the 50 wt% hBN/10 wt% AlS formulation achieving 7.992 W/(m K) in-plane and 1.785 W/(m K) through-plane, 3059% and 738% improvements over neat PEEK. Those with higher AlS content demonstrated improved mechanical properties, with 10 wt% hBN/50 wt% AlS composite reaching tensile strength of 96.31 MPa, matching neat PEEK and outperforming single filler hBN/PEEK by 44%. Rheological studies revealed shear-thinning behavior of hybrid composites, with melt viscosity tunable by adjusting filler ratios. The composites also maintained excellent thermal stability under typical operating temperatures (≤ 250°C). Thus, current work presents a scalable co-extrusion process for developing robust, thermally conductive hybrid PEEK composites by addressing the critical challenge of co-optimizing thermal conductivity and mechanical strength, positioning these materials as strong candidates for high-performance thermal management applications.