PLA/Graphene/MWCNT Composites with Improved Electrical and Thermal Properties Suitable for FDM 3D Printing Applications

Verislav Angelov,Anna Godoy,Sossio Cimmino,Hesheng Xia,Ricardo Donato,Rosa Di Maio,Rumiana Kotsilkova,Clara Silvestre,Evgeni Ivanov,Yinghong Chen,Katarzyna Donato

doi:10.3390/app9061209

Abstract

In this study, the structure, electrical and thermal properties of ten polymer compositions based on polylactic acid (PLA), low-cost industrial graphene nanoplates (GNP) and multi-walled carbon nanotubes (MWCNT) in mono-filler PLA/MWCNT and PLA/GNP systems with 0–6 wt.% filler content were investigated. Filler dispersion was further improved by combining these two carbon nanofillers with different geometric shapes and aspect ratios in hybrid bi-filler nanocomposites. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy exhibited uniform dispersion of nanoparticles in a polymer matrix. The obtained results have shown that for the mono-filler systems with MWCNT or GNP, the electrical conductivity increased with decades. Moreover, a small synergistic effect was observed in the GNP/MWCNT/PLA bi-filler hybrid composites when combining GNP and CNT at a ratio of 3% GNP/3% CNT and 1.5% GNP:4.5% CNT, showing higher electrical conductivity with respect to the systems incorporating individual CNTs and GNPs at the same overall filler concentration. This improvement was attributed to the interaction between CNTs and GNPs limiting GNP aggregation and bridging adjacent graphene platelets thus, forming a more efficient network. Thermal conductivity increases with higher filler content; this effect was more pronounced for the mono-filler composites based on PLA and GNP due to the ability of graphene to better transfer the heat. Morphological analysis carried out by electron microscopy (SEM, TEM) and Raman indicated that the nanocomposites present smaller and more homogeneous filler aggregates. The well-dispersed nanofillers also lead to a microstructure which is able to better enhance the electron and heat transfer and maximize the electrical and thermal properties. The obtained composites are suitable for the production of a multifunctional filament with improved electrical and thermal properties for different fused deposition modelling (FDM) 3D printing applications and also present a low production cost, which could potentially increase the competitiveness of this promising market niche.

Highlights

In the last few years, 3D printing has emerged as a leading manufacturing technology all over the world for a variety of applications
A homogeneous dispersion of multi-walled carbon nanotubes (MWCNT) and graphene nanoplates (GNP) in polymeric melts is essential to prepare enhanced filler-based filaments, since heterogeneity can be detrimental to Fused Deposition Modeling technology (FDM), possibly causing blockages at the nozzle and flux instability while printing
The results show that at maximum filler content (6 wt.%) electrical conductivity increases almost 7–8 decades for the two-component systems with GNP and MWCNT compared with pure polylactic acid (PLA), reaching the values of 8.4 × 10−3 (S/m) and 2.1 × 10−2 (S/m), respectively

Summary

Introduction

In the last few years, 3D printing has emerged as a leading manufacturing technology all over the world for a variety of applications. Carbon nanotubes (CNT) and graphene are state of the art and very promising carbonaceous materials. Their high specific surface area allows low loadings in order to tune polymer key properties concerning mechanical, thermal, electrical, and biological performance. CNT have exceptional mechanical properties, aspect ratio, electrical and thermal conductivities, and chemical stability These characteristics make them excellent candidates for the creation of multifunctional materials either in the field of polymer composites or other application [4,5,6,7,8,9,10,11,12,13]. Based on the unique properties of graphene, the graphene-based polymer composites are expected to offer superior mechanical properties, enhanced electrical and thermal conductivity, improved dimensional stability, higher resistance to microcracking, and increased barrier properties above the matrix polymer [14,15,16,17,18]

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Results

Conclusion