Abstract
In the present study, polylactic acid (PLA) enriched with carbonaceous particles like multi-walled carbon nanotubes (MWCNTs), graphene nanoplates (GNPs) or a combination of both up 12 wt % of loading are used for producing 3D-printed specimens with fused deposition modeling (FDM) technology which are then experimentally and theoretically investigated. The goal is to propose a non-conventional filaments indicated for additive manufacturing process with improved dielectric and thermal properties, compared to the performances exhibited by the unfilled polymer. In the light of the above, a wide dielectric spectroscopy and a thermal analysis, supported by a morphological investigation, are performed. The results highlight that the introduction of 1-dimensional filler (MWCNTs) are more suitable for improving the dielectric properties of the resulting materials, due to the enhancement of the interfacial polarization and the presence of functionalized groups, whereas 2-dimensional nanoparticles (GNPs) better favor the thermal conduction mechanisms thanks to the lower thermal boundary resistance between the two phases, polymer/filler. In particular, with a loading of 12 wt % of MWCNTs the relative permittivity reaches the value of 5.35 × 103 much greater than that of 3.7 measured for unfilled PLA while for the thermal conductivity the enhancement with 12 wt % of GNPs is about 261% respect the thermal behavior of the neat polymer. The experimental results are correlated to theoretical findings, whereas a design of experiment (DoE) approach is adopted for investigating how the different fillers influence the dielectric and thermal performances of the 3D-printed parts, thus assisting the design of such innovative materials that appear promising for development and applications in the electromagnetic (EM) field and heat transfer.
Highlights
Additive manufacturing (AM), known as 3D-printing or rapid prototyping, has been growing rapidly given the amazing feature to convert a digital 3D model into a solid structure, without shape complexity limits, by depositing suitable materials layer by layer [1]
As feedstock for such AM technique non-conventional filaments of poly(lactic) acid (PLA) reinforced with multi-walled carbon nanotubes (MWCNTs), graphene nanoplates (GNPs) or combinations thereof, in different weight ratios (i.e., 1:1; 3:1, 1:3), up to 12 wt % of loading have been formulated and developed
Polymers 2020, 12, x FOR PEER REVIEW. It highlights specific 3D printing features such as odorless, remarkable thermal properties and faster activity. It highlights specific 3D printing features such as odorless, remarkable thermal properties crystallization rate, which lead to a clear improvement of the adhesion to platform plates and to an and faster crystallization rate, which lead to a clear improvement of the adhesion to platform plates increasing of the printing speed
Summary
Additive manufacturing (AM), known as 3D-printing or rapid prototyping, has been growing rapidly given the amazing feature to convert a digital 3D model into a solid structure, without shape complexity limits, by depositing suitable materials layer by layer [1]. Composite scaffolds of different materials (including PLA due to its biocompatibility) for the generation design and manufacturing of medical implants, especially in bone tissue engineering, were proposed, produced and structurally and mechanically investigated in micro and nanoscale [14,15,16]. Differently from the aforementioned papers, a morphological characterization, a wide dielectric spectroscopy and a thermal analysis are performed on 3D-printed specimens with FDM technology. As feedstock for such AM technique non-conventional filaments of PLA reinforced with multi-walled carbon nanotubes (MWCNTs), graphene nanoplates (GNPs) or combinations thereof, in different weight ratios (i.e., 1:1; 3:1, 1:3), up to 12 wt % of loading have been formulated and developed. The proposed theoretical investigations aim to support the experimental activity in the design of these novel materials that appear promising candidates for multifunctional applications related to EM compatibility, conductivity and heat transfer
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