Processing and mechanical properties of HA/UHMWPE nanocomposites

A hydroxyapatite (HA) particulate reinforced ultrahigh molecular weight polyethylene (UHMWPE) nanocomposite was fabricated by compounding HA and UHMWPE mixtures in paraffin oil using twin-screw extrusion and then compression molding. Scanning electron microscope images revealed that HA aggregates were broken down to nano-sized particles and homogeneously dispersed in UHMWPE by the combined processes of twin-screw extrusion and UHMWPE swelling treatment. Transmission electron microscope images indicated the HA particles and UHMWPE matrix were intimately contacted through mechanical interlocking. The composite with the HA volume fraction of 0.23 exhibited a Young's modulus nine times higher than that of UHMWPE, while the composite maintained the excellent toughness feature of UHMWPE. The fracture strain reached over 300%, significantly higher than other types of biocomposites.