Mechanical and thermal properties and cytotoxicity of Al₂O₃ nano particle-reinforced poly(ether-ether-ketone) for bone implants

Weak mechanical properties and mismatching of elastic modulus to human bone restricts the use of PEEK as a bone implant material. By introducing reinforcing particles in polymers, composite material properties could be tailored to meet specific design requirements. In this work, composite materials with PEEK as a matrix and Al₂O₃ as reinforcing fillers were prepared by an injection molding method. Subsequently, the effects of different particle sizes (30 nm, 0.2 μm, 5 μm) and distinct contents (2.5 wt%, 5.0 wt%, 7.5 wt%, 10.0 wt%, 12.5 wt%, 15.0 wt%) of Al₂O₃ powder on the mechanical properties of the composites, such as tensile strength, bending strength, impact strength, Vickers hardness and modulus, were investigated by an electronic universal testing machine. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to compare the thermal properties of composites with different proportions. Besides, the cross-section fractography of the composites after the tensile strength test was characterized by scanning electron microscopy (SEM) to analyze the interface bonding effect. Moreover, mouse fibroblast L929 cells were used for cytotoxicity testing of CCK-8 kit to evaluate cell compatibility of the composite in vitro and cell morphology was observed by inverted fluorescence microscopy. Based on the obtained results, Al₂O₃ reinforcement enhanced many properties in some aspects, which makes the Al₂O₃/PEEK composite one of the most promising candidates for human bone implantation, reconstruction, orthopedic and trauma applications.