Enhanced mechanical properties of CF/PEEK and CF/Epoxy composites with micro-/nano- Aramid Pulp interleaves

Carbon fiber-reinforced polyetheretherketone (CF/PEEK) composites with excellent biomedical properties have been used clinically for bioimplants, but mechanical failure due to delamination remains a concern. This study explores the use of micro-/nano- Aramid Pulp (AP) fibers to enhance the delamination toughness of CF/PEEK composites. Furthermore, AP-interfacial toughened CF/PEEK composites are compared with common carbon fiber-reinforced epoxy (CF/Epoxy) composites. The findings revealed that AP toughening increased the compressive strength of CF/PEEK composites by 41%, improved flexural-after-impact (FAI) strength by 19%, and reduced the rear surface delamination area by 51 %. It was also found that the flexural failure of CF/PEEK composites is initiated from the tensile surface, in contrast to CF/Epoxy composites, which undergo initial delamination and micro-buckling in the compression region. Additionally, AP-interfacial toughening has effectively eliminated top surface compressive cracks in CF/PEEK composites under flexural conditions despite its tension-driven failure mechanism. Consequently, besides the comparison of CF/PEEK and CF/Epoxy composites, this study provides valuable insights into minimizing mechanical failures of CF/PEEK implants in patients, where delamination is a major contributing factor.