Ionic liquid lubricants of PLA. New self-lubricating (PLA+ionic liquid) materials

Friction coefficients and wear rates of polylactic acid (PLA)-stainless steel pair have been determined under two different contact configurations using four aprotic imidazolium and a bio-based protic ammonium ionic liquid (IL) lubricants. Under rotational pin-on-disk, all ILs reduce friction coefficient in more than one order of magnitude and prevent wear. Under linear reciprocating sliding, the best performance is found for the halogen-free protic ammonium IL, with the highest viscosity and lower contact angle values. New (PLA+IL) materials have been obtained and excellent self-lubricating performance has been found for those with a porous surface. Results are discussed upon the basis of rheology, contact angles, surface topography and electron microscopy (SEM/EDX) studies.