Enhanced Interfacial and Tribological Properties of Polyether Ether Ketone Composites by the Addition of Modified Carbon Fibers

Carbon fiber (CF)‐reinforced polyether ether ketone (PEEK) composites exhibit excellent comprehensive properties. However, the inert surface and poor wettability of CF reduce the interfacial performance in CF/PEEK composites, thereby limiting their applicability in harsh environments. To address this limitation, CF was chemically grafted using two modifiers: a polyethyleneimine (PEI) sizing agent containing carboxylated multi‐walled carbon nanotubes (MWCNTs), and a polyamidoamine (PAMAM) coupling agent also containing carboxylated MWCNTs. The amino groups in PEI and PAMAM can form amide bonds with carboxylated CF. Additionally, the long‐chain structure of PEI physically entangles the CF, and its π–π conjugation with the PEEK matrix enhances interfacial bonding. As a result, CF‐PEI‐MWCNTs/PEEK composites (0.3 wt.% MWCNTs) demonstrated superior interfacial properties compared to CF‐PAMAM‐MWCNTs/PEEK composites (0.5 wt.% MWCNTs). The wear resistance of the composite is improved, and the wear mechanism changes from plastic deformation to mild adhesive wear.