MECHANICAL, TRIBOLOGICAL AND CYTOTOXICITY CHARACTERIZATION OF SODIUM HYDROGELS REINFORCED WITH CARBON NANOTORI

Sodium alginate (SA) hydrogels reinforced with different concentrations (0, 0.01 and 0.05 wt.%) of Carbon Nanotori (CN) were characterised to determine their mechanical, tribological and cytotoxicity properties. For the mechanical tests, a crosslinking agent was added to obtain solid hydrogels, whereas for the tribological tests SA/CN hydrogel samples were analysed in a liquid state. In the cytotoxicity tests, the C6 cells proliferation was evaluated in the presence of CN at various dilutions. In the tensile tests the hydrated-hydrogel strips reinforced with 0.1 wt.% CN obtained an UTS of 44.43 MPa, representing an enhancement of 133% compared to the un-reinforced hydrogel. In the compression tests an increase of only 3.4% in the UCS was obtained with the addition of 0.05 wt.%. Tribological characterization showed an enhancement of up to 37% and 105% in seizure load (P oz) and load-carrying capacity (poz), respectively with 0.05 wt.% CN. The wear scar diameter at this concentration was reduced by ~19%. The results of the cytotoxicity tests confirmed that CN are not cytotoxic since they did not reduce C6 cell proliferation.