Improving the impact strength of Poly(lactic acid) (PLA) in fused layer modeling (FLM)

Polylactic acid (PLA) is one of the most popular thermoplastics for fused deposition modeling (FDM). Attributed to its semi-crystalline nature, the relation between printing parameters and properties are more complicated than amorphous thermoplastics like acrylonitrile-butadiene-styrene (ABS). This study was designed to investigate two printing parameters, layer height (0.2 and 0.4 mm) and plate temperature (30 and 160 degrees C) on the Izod impact strength of printed PLA. X-ray diffraction (XRD) analysis confirmed the existence of a crystals in parts printed from 160 degrees C-plate temperature and alpha' crystals in those printed at 30 degrees C-plate temperature. Parts printed with a 160 degrees C (plate temperature) had higher crystallinity. Polarized optical microscope (POM) observations illustrated that the plate temperature of 160 degrees C and layer height of 0.2 mm induced higher crystallinity, smaller crystals and interfacial crystal bands. The Izod impact strength of printed PLA at higher plate temperature was up to 114% higher than injection molded PLA made using conventional molding parameters. (C) 2017 Elsevier Ltd. All rights reserved.