Tailoring the Mechanical and Thermal Properties of PEEK with Hydroxyapatite Addition for Enhanced Orthopedic Performance

Abstract

This study focuses on developing bioactive PEEK composites for orthopedic and dental applications. While PEEK offers excellent strength, biocompatibility, and radiolucency, its biological inertness limits bone integration. Incorporating hydroxyapatite (HA) enhances PEEK’s bioactivity, improving osseointegration and bone cell adhesion for medical implants. The PEEK and PEEK/HA (20% HA) composites were fabricated using twin-screw extrusion and injection molding, ensuring uniform HA dispersion within the matrix. Scanning electron microscopy (SEM) revealed increased surface roughness in PEEK/HA composites due to HA particles, improving cell adhesion and tissue integration. Differential scanning calorimetry (DSC) indicated that HA acts as a nucleating agent, raising crystallinity from 31.89% to 42.86%, enhancing rigidity and thermal stability without altering the melting temperature. Mechanical testing showed that HA addition increased maximum stress by 10.94% and Young’s modulus by 30.07%. In fact, pure PEEK offers a maximum stress of 96.83 MPa, a modulus of 2.96 GPa and a strain of 54.9%, combining strength and elasticity. With 20% HA, the stress reaches 107.43 MPa and the modulus 3.85 GPa, increasing stiffness and strength, but reducing the strain to 35.04%. This balance between enhanced stiffness and reduced flexibility makes PEEK/HA composites suitable for load-bearing applications like orthopedic implants.