Rheological and tribological behavior of new 3D‐printed poly(lactic acid) modified by ionic liquid

Poly(lactic acid) (PLA) modified by addition of the ionic liquid (IL) 1‐butyl‐1‐methylpyrrolidinium hexafluorophosphate was processed by extrusion followed by 3D printing to obtain (PLA + IL). The presence of the IL enhances polymer chain mobility, increasing its fluidity. Variation of storage and loss modulus with strain percentage indicates that the presence of the IL additive reduces strain resistance, decreasing the viscoelastic properties. Reciprocating tribological tests have been carried out on the high‐roughness surfaces of as‐printed PLA and (PLA + IL), under sliding parallel and perpendicular to the 3D printing direction. The addition of IL reduces friction coefficients with respect to unmodified PLA, shifting the transition to high‐steady‐state friction to longer distances for (PLA + IL). The highest average friction reduction (45%) is observed for sliding perpendicular to the 3D printing direction. This effect is attributed to a better layer adhesion in (PLA + IL). Surface damage is studied by profilometry and scanning electron microscopy. A very mild polishing effect with unmeasurable wear is observed on the wear paths. Short‐term degradability studies of 3D printed films in seawater indicating differences between both materials have been carried out.