Impact of the Fused Deposition (FDM) Printing Process on Polylactic Acid (PLA) Chemistry and Structure

Abstract

Polylactic Acid (PLA) is an organic polymer commonly used in fused deposition (FDM) printing and biomedical scaffolding that is biocompatible and immunologically inert. However, variations in source material quality and chemistry make it necessary to characterize the filament and determine potential changes in chemistry occurring as a result of the FDM process. We used several spectroscopic techniques, including laser confocal microscopy, Fourier-Transform Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 3 April 2017 doi:10.20944/preprints201704.0010.v1Peer-reviewed version available at Appl. Sci. 2017, 7, , 579; doi:10.3390/app7060579 Infrared (FTIR) spectroscopy and photoacousitc FTIR spectroscopy, Raman spectroscopy, and X-ray photoelectron Spectroscopy (XPS) in order to characterize both the bulk and surface chemistry of the source material and printed samples. Scanning Electron Microscopy (SEM) and Differential Scanning Calorimetry (DSC) were used to characterize morphology, crystallinity, and the glass transition temperature following printing. Analysis revealed calcium carbonatebased additives which were reacted with organic ligands and potentially trace metal impurities, both before and following printing. These additives became concentrated in voids in the printed structure. This finding is important for biomedical applications as carbonate will impact subsequent cell growth on printed tissue scaffolds. Results of chemical analysis also provided evidence of the hygroscopic nature of the source material and oxidation of the printed surface, and SEM imaging revealed micro and sub-micron scale roughness that will also impact potential applications.

The Study of Physico-Mechanical Properties of Polylactide Composites with Different Level of Infill Produced by the FDM Method

“…These are very important factors that make it necessary to focus on this polymer during engineering design. In the case of biodegradation, PLA can be subjected to industrial composting, which makes PLA degradable in 100% [ 52 , 53 , 54 ]. Hydrolytic degradation is the basis for the recycling.…”

Application of 3D Printing in Implantable Medical Devices

“…3D printing is also known as additive manufacturing; it is done through layer-by-layer stacking techniques, and according to the designed 3D model, complex and diverse physical entities can be manufactured [ 4 ]. Common manufacturing processes for 3D printing include Stereo Lithography Apparatus (SLA) [ 5 ], Laminated Object Manufacturing (LOM) [ 6 ], Selective laser Sintering (SLS) [ 7 ], Fused Deposition Modeling (FDM) [ 8 ], and Three-Dimensional Printing (3DP) [ 9 ].…”

Biodegradable Poly(Lactic Acid) Nanocomposites for Fused Deposition Modeling 3D Printing

“…Importantly, Cicala et al determined that polymers with high viscosity print with increased precision because of their resistance to flow after printing, which allows them to hold their shape and minimize voids between printed layers [ 35 ]. Cuiffo et al investigated commercial PLA samples with calcium carbonate additives and found that the CaCO 3 concentrated in the voids of the 3D-printed materials after FDM printing [ 36 ]. Additionally, these PLA samples underwent minor chemical reactions during the FDM process, as shown by changes in the Fourier transform infrared (FTIR) stretches for the C=O, C–O–C, -CH 3 , and -OH functional groups, and by deviations in the cold crystallization (T cc ) and melting (T m ) temperatures [ 36 ].…”

“…Neat PLA has a T g of 55–65 °C [ 36 , 37 ] and T m of 173–178 °C [ 36 ], which enables FDM printing. While the thermal and mechanical properties of PLA are appropriate for FDM 3D printing, they are often inappropriate for many applications, which require a different set of properties.…”