Carbon nanotube functionalization supports mechanical, tribological, and biological response of freeze-dried ultra-high molecular weight polyethylene-based bio-composites

Acetabular cup liners made of ultra-high molecular weight polyethylene (UHMWPE), in hip implants fail mostly due to wear debris generation and poor wear resistance. Consequently, strengthening UHMWPE becomes essential. The current work exhibits how the addition of 5 vol% carbon nanotubes (CNT) and functionalized carbon nanotubes (fCNT) in UHMWPE (denoted as U) affects the mechanical properties (hardness, elastic modulus) and tribological properties (wear resistance) of biocomposites. To form a composite, powders were mixed using a planetary centrifugal mixer followed by freeze-drying to disperse-CNTs, followed by its compression molding at 220 degrees C for 1 h at 10 MPa. With the addition of CNT and fCNT, >= 95% densification was obtained for all samples resulting an increase in hardness and elastic modulus from 74.96 MPa to 168.11 MPa (124%) and 1.65 GPa to 2.96 GPa (79%), respectively, which led to the reduction in wear rate from 12.5 x 10-5 mm3/Nm (U) to 2.5 x 10-5 mm3/Nm (UfCNT). The amount of apatite formation enhanced from U (58.2%) to UfCNT (65.1%) is confirmed via X-ray diffraction and X-ray photoelectron spectroscopy. Cell proliferation studies have validated the cytocompatible efficacy of U-CNT composites with osteoblast-like MG-63 cells, making UfCNT as potential material for acetabular cup liners. The role of CNT functionalization on hardness, elastic modulus, fretting wear scar, contact angle, apatite formation, and cell proliferation of (a) UCNT and (b) UfCNT composites. image