Exploration of Additively manufactured Microcellular PLA

Abstract

This thesis investigates the 3D printing of Polylactic Acid (PLA) using CO2-saturated filament, comparing it with the solid-state microcellular foaming process. The study examines the impact of various 3D printer nozzle temperatures (180°C to 210°C) and CO2 saturation pressures (1 MPa to 4 MPa) on the mechanical properties of PLA. The study reveals that when PLA sheets are 3D printed and undergoes the solid-state foaming process, we see porous structure with decent reduction in relative density and tensile strength but with a very high strain to failure performance. Whereas, when saturated PLA filament is used to 3D print specimens, all the gas escapes when the PLA melts and only a fraction of gas is present at atmospheric pressure which results in a very low porosity (void structure of ~10%). Additionally, higher saturation pressures enhance gas uptake but result in crystallization. Tensile tests show a 10-15MPa reduction in tensile strength when compared to untreated 3D printed dogbone samples of tensile strength ~50MPa. These findings contribute to understanding the limitations and potential improvements in the mechanical properties of 3D printed PLA for industrial applications.