Enhanced Mechanical, Thermal and Antimicrobial Properties of Additively Manufactured Polylactic Acid with Optimized Nano Silica Content

Nectarios Vidakis; Markos Petousis; Emanuel Velidakis; Nikolaos Mountakis; Lazaros Tzounis; Marco Liebscher; Sotirios A Grammatikos

doi:10.3390/nano11041012

Enhanced Mechanical, Thermal and Antimicrobial Properties of Additively Manufactured Polylactic Acid with Optimized Nano Silica Content

Nanomaterials (Basel). 2021 Apr 15;11(4):1012. doi: 10.3390/nano11041012.

Authors

Nectarios Vidakis¹, Markos Petousis¹, Emanuel Velidakis¹, Nikolaos Mountakis¹, Lazaros Tzounis², Marco Liebscher³, Sotirios A Grammatikos⁴

Affiliations

¹ Mechanical Engineering Department, Hellenic Mediterranean University, 71410 Heraklion, Greece.
² Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina, Greece.
³ Institute of Construction Materials, Technische Universität Dresden, DE-01062 Dresden, Germany.
⁴ Department of Manufacturing & Civil Engineering, NTNU-Norwegian University of Science and Technology, Building B', Teknologivegen 22, 2815 Gjøvik, Norway.

Abstract

The scope of this work was to create, with melt mixing compounding process, novel nanocomposite filaments with enhanced properties that industry can benefit from, using commercially available materials, to enhance the performance of three-dimensional (3D) printed structures fabricated via fused filament fabrication (FFF) process. Silicon Dioxide (SiO₂) nanoparticles (NPs) were selected as fillers for a polylactic acid (PLA) thermoplastic matrix at various weight % (wt.%) concentrations, namely, 0.5, 1.0, 2.0 and 4.0 wt.%. Tensile, flexural and impact test specimens were 3D printed and tested according to international standards and their Vickers microhardness was also examined. It was proven that SiO₂ filler enhanced the overall strength at concentrations up to 1 wt.%, compared to pure PLA. Atomic force microscopy (AFM) was employed to investigate the produced nanocomposite extruded filaments roughness. Raman spectroscopy was performed for the 3D printed nanocomposites to verify the polymer nanocomposite structure, while thermogravimetric analysis (TGA) revealed the 3D printed samples' thermal stability. Scanning electron microscopy (SEM) was carried out for the interlayer fusion and fractography morphological characterization of the specimens. Finally, the antibacterial properties of the produced nanocomposites were investigated with a screening process, to evaluate their performance against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus).

Keywords: Charpy’s impact test; Vickers microhardness; additive manufacturing (AM); flexural test; nanocomposites; polylactic acid (PLA); scanning electron microscopy (SEM); silicone dioxide (SiO2); tensile test; three-dimensional (3D) printing.