Covalent-Bond Modified Boron Nitride for High-Temperature Poly(Ether Ether Ketone) Composites: Enhancement of Thermal Conductivity and Mechanical Properties by Interfacial Strengthening

Interface thermal resistance is the key factor in influencing the thermal conductivity of filler-reinforced composites. Building a covalent-bond bridge between the resin and filler effectively reduces the interface thermal resistance by creating thermal transmission pathways. A covalent-bonded poly (ether-ether-ketone)/boron nitride (PEEK/BN) composite (i-PEEK/BNNS-FOH) was prepared by functionalizing BN and incorporating it into the in situ polymerization process. With an addition of 30 wt% functionalized BN, the thermal conductivity of i-PEEK/BNNS-FOH reached 1.79 W m −1 K −1 , an increase of 12% over ungrafted PEEK/BN. Foygel's model calculations proved that the modification of BN reduced interface thermal resistance by 48%. Additionally, the improved interface contributed to better mechanical properties, reaching a tensile strength of 97 MPa with a 10 wt% filler addition. This covalent-bond bridging strategy highlights modified BN fillers for high-temperature applications and an efficient method for the preparation of thermally conductive special engineering plastics.