• E-poster title: The importance of melting in 3D printing
• Author(s): Targol Hashemi1,*, Sara Liparoti1 , Dario Cavallo2 , Maria Laura Di Lorenzo3 , Roberto Pantani1
• Affiliation(s) (e.g., institution):
1 Department of Industrial Engineering, University of Salerno, via Giovanni Paolo II, 132, Fisciano (SA), Italy
2 Department of Chemistry and Industrial Chemistry - University of Genoa, Via Dodecaneso 31, 16146, Genova, Italy
3 National Research Council (CNR) - Institute of Polymers, Composites and Biomaterials (IPCB), Via Campi Flegrei, 34, 80078 Pozzuoli, NA, Italy
• Abstract (as plain text):
Additive manufacturing, namely 3D printing, is attracting increasing interest in the industrial field since it allows obtaining parts with complex shape that are challenging to obtain with conventional processes. In particular, 3D printing of polymers is able to construct the object through the deposition of extruded bead on a deposition plate [1]. Although interesting, 3D printing of polymers is challenging due to several phenomena that are not completely understood. For instance, the presence of crystallization seeds, cause to an incomplete melting, induces a faster crystallization with consequent effects on the adhesion between adjacent beads [2]. If the crystallization is faster than the reorganization of molecules at the interface between adjacent beads, the molecules will not interact, and the adhesion will be poor. Otherwise, if crystallization occurs later in the process, it will increase the interaction at the interface, and the adhesion will be strong [3]. This work aims at assessing the effect of previous crystallization on the mechanical performances of 3D printed parts. A polylactic acid (PLA) filament has been obtained by extrusion and annealed at different temperatures to achieve desired crystallization degree. The filament has been used during the process conducted with different extrusion ratios to obtain the parts. The higher the extrusion ratio, which means flow rate, the higher the crystallinity and the orientation of the part are. The crystallinity degree and the orientation achieved during the process are correlated with the residence time of polymer inside the extruder.