Bio-based materials in tribology: New salicylate ionic liquid+ZnO nanolubricant of PLA and PLA nanocomposite
Clara C. Sánchez-Rodríguez, Ramón Pamies, J. Sanes, F.J. Carrión, Marı́a-Dolores Bermúdez
Abstract
ZnO nanoparticles have been dispersed (in 0.05; 0.5 and 1.0 wt% proportions) in the protic ionic liquid bis(2-hydroxyethyl) ammonium salicylate (DSa) to obtain new (DSa+ZnO) nanofluids. A non-Newtonian behavior was found for ZnO concentrations lower than 1 wt%. The Newtonian DSa+ 1 wt%ZnO nanofluid was selected as lubricant of polylactic acid (PLA) and as 5 wt% additive to obtain the new PLA+ (DSa+ZnO) nanocomposite. PLA+ZnO was also studied as a reference. The excellent friction-reducing and antiwear behavior of PLA+ (DSa+ZnO) is attributed to the porosity that promotes self-lubrication and to synergy due to interactions between the salicylate anion in DSa and the surface of ZnO nanoparticles. Electron microscopy (SEM and TEM), Raman spectroscopy, thermal analysis (DSC and TGA) and profilometry techniques were used.