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

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).

Polymer Composites Based on Polycarbonate (PC) Applied to Additive Manufacturing Using Melted and Extruded Manufacturing (MEM) Technology

“…The exceptions are composites obtained by the injection method PC/3%S and PC/3%L, which had better impact resistance (Figure 7b). It should be mentioned that analogous results of impact tests for composites containing selected fillers are described in the literature [43,44]. Based on the results of the impact tests, it was found that both the content and the type of filler had an effect on the tested property.…”

“…The exceptions posites obtained by the injection method PC/3%S and PC/3%L, which had bette resistance (Figure 7b). It should be mentioned that analogous results of impact composites containing selected fillers are described in the literature [43,44]. The morphology of brittle fractures of the obtained composites was analyzed using scanning electron microscopy (SEM).…”

“…The exceptions are composites obtained by the injection method PC/3%S and PC/3%L, which had better impact resistance ( Figure 7 b). It should be mentioned that analogous results of impact tests for composites containing selected fillers are described in the literature [ 43 , 44 ].…”

On the Mechanical Response of Silicon Dioxide Nanofiller Concentration on Fused Filament Fabrication 3D Printed Isotactic Polypropylene Nanocomposites

“…However, they may induce some processability issues to the FFF 3D melt filamentous printing process. This is due to the well-known abrupt increase of the polymer melt viscosity, associated with the nanoparticle inclusions hindering the polymer chain mobility in the melt state, which may result in a deteriorated quality of the 3D printed final objects [ 17 , 18 , 19 , 20 ]. It is of great scientific interest thus to develop polymer (nano-)composites able to be processed through AM technologies without compromising mechanical, thermal and other inherent properties of the matrix host material [ 6 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ].…”

“…Silicon dioxide is also utilized as filler in polymer-based composites [ 30 , 31 , 32 , 33 ]. Targeting to increase microwave absorption, antimicrobial performance, mechanical properties, etc., silica can be used as a dispersed phase in polymeric materials [ 20 , 34 ]. In many cases SiO 2 is also accrued as to improve processability of polymers in different manufacturing methods [ 20 , 35 ].…”