Synthesis and Characterization of Carbon Nanotubes Reinforced Hydroxyapatite Composite

Hydroxy Apatite (HA), as a bone mineral component, has been an attractive bioceramic for the reconstruction of hard tissues. However, its poor mechanical properties, including low fracture toughness and tensile strength, have been a significant challenge to the application of HA for the replacement of load-bearing and/or large bone defects. 0.5 M Ca(NO₃)₂.4H₂O and 0.5 M (NH₄)₂HPO₄ were used to synthesize HA in situ. Multiwalled Carbon Nanotubes were functionalized by heating at 100°C in 3:1 ratio of 20% H₂SO₄ and 20% HNO₃ for 60 m with stirring. Functionalized MWCNTs were dispersed in Sodium Dodecyl Benzene Sulphonate (SDBS) (10g L⁻¹) by sonication. Hydroxy Apatite (HA) particles were produced in MWCNTs solution by adding 0.5 M Ca(NO₃)₂.4H₂O and 0.5 M (NH₄)₂HPO₄ under vigorously stirring conditions. The composite were dried at 60°C followed by washing in distilled water for 3 to 4 times. Heat treatment at 250°C was done for 30 min to obtain CNT-HA powder. Solution of Polyvinyl Alcohol (PVA) (10g L⁻¹) was made by stirring correct quantities of polymer and distilled water at 90°C continuously for 2h. The MWCNT solution in SDBS and MWCNT-HA composite, which has been prepared in advance, was added to the PVA solution and sonicated for 2h in a sonic bath followed by subsequently casting, and controlled water evaporation. PVA/MWCNTs and PVA/MWCNTs/HA composite films were obtained by peeling off from the glass plate substrates and kept in a vacuum desiccator until analyzed. Using FTIR, FESEM, EDS and UTM perform physicochemical characterization of the composite material. FTIR shows the attachments of PO4 and CO3 groups on the composites, which has been further investigated by FESEM and EDS analysis. The EDS results confirmed the presence of the elements such as Ca, P and C in the respective samples. The FESEM confirms HA nanoparticles are densely decorated on MWCNTs. The UTM results shows that overall mechanical properties of the MWCNT-HA composites are significantly improved with increasing concentration of MWCNTs as compared to the PVA film. The organization of CNTs and HA implemented at the nanoscale can further be developed in the form of coatings, nanocomposites, and hybrid powders to enable potential applications in hard tissue reconstruction.