Effect of Filament Pre-Drying on the Microstructure and Porosity of 3D Printed PLA

Abstract

This paper explored the effect of filament pre-drying before 3D printing. A comparison between the undried and pre-dried 3D printed PLA was evaluated in terms of porosity, microstructure, and polymeric chain bonding. Three conditions were examined: a new PLA as a reference, used PLA filament stored in a vacuumed bag with 50g desiccant, and used PLA exposed to humidity for 48h, 96h, and 150h. The parameter setting for drying and 3D printing was constant for all conditions. As a result, pre-drying the filament resulted in a less porous microstructure, shorter interlayer gap, and better interlayer adhesion. The pre-drying method offers a better microstructure than undried filament. The density of the pre-dried sample was increased as the porosity decreased due to the improvement in the mass flow rate upon the extrusion process. Lastly, the FTIR analysis shows that the pre-dried filament exhibits an O-H molecule free from the O-H region broad peak, which shows no or almost no presence of water (H₂O).