Wear Behavior of 3D Printed PLA Surfaces for Superhydrophobic Interaction

Polylactic Acid (PLA) is a biodegradable thermoplastic polymer known for its widescale application in bio-tribology. A known problem with PLA is its high level of water adsorption due to its hydrophilic nature which can lead to growth of mold and other fungal derivatives due to water stagnation. In our investigation we developed a re-entrant pattern using a standard fused-deposition modelling (FDM) 3D printer with the aim to achieve surfaces which are superhydrophobic in nature. The layer heights of the re-entrant profiles were systematically modified while keeping all other printing parameters constant to achieve a multi-edge ladder effect. The samples were then investigated for their superhydrophobic characteristics by measurement of Contact and Tilt Angles and thereafter characterized for wear resistance using a ball-on-disc tribometer. A fixed low rpm setting was used to eliminate the effect of temperature. Wear parameters including Wear Depth and Coefficient of Friction were recorded after each cycle using until the sample’s re-entrant structure was damaged and no longer supported water-repellent behavior shown by a considerable decrease in water contact angle. The effect of layer height variation in the re-entrant profiles for effective wear resistance was established as a preliminary study for our subsequent research in the area. It can be concluded that the layer height plays a vital role in achieving superhydrophobicity and has a direct influence on the wear resistant of the surface.