Effect of notch sensitivity on the mechanical properties of HA/PEEK functional gradient biocomposites

Abstract Biomaterials used as loading-bearing orthopedic implants usually require various excellent properties such as mechanical, bioactive and bio-tribological performances. Moreover, all of the orthopedic applications feature stress concentrations (notch sensitivity) in their design. In the present work, hydroxyapatite-reinforced polyetheretherketone functional gradient biocomposites (HA/PEEK FGBm) were successfully prepared by the layer stacking method combined with hot pressing molding technology. The effects of notch geometry on the stress-strain behavior of HA/PEEK FGBm were evaluated. The fracture morphology was investigated by scanning electron microscopy (SEM). The study of the stress-strain behavior indicated that the tensile and flexural stresses of HA/PEEK FGBm linearly increased with increasing strain under all the notch sensitivities. The fracture strain of the biocomposites decreased with increasing stress concentration factor and total HA content in the functional biocomposites. Moreover, the tensile and flexural strengths of HA/PEEK FGBm were lower than those of homogeneous HA/PEEK biocomposites. The SEM observation of the fracture micro-morphology showed that the fracture mechanism of HA/PEEK FGBm was gradually controlled by the brittle fracture process. Furthermore, both the tensile and the flexural strengths of HA/PEEK FGBm decreased with the increase in stress concentration factor and total HA content in the biocomposites.