3D-Printed Conductive Filaments Based on Carbon Nanostructures Embedded in a Polymer Matrix: A Review

Introduction

3DP is revolutionizing the world, computer designed objects fabricated using 3D-printers can be more complex than conventionally machined parts, such emergent manufacturing technology promises to boost the fabrication of highly sophisticated parts directly from computer-aided designs. Now it is possible to 3DP lightweight structures with high dimensional accuracy at lower cost for customized geometries (Chua & Leong 2016). Over the past few years, the intrinsic limitations of neat polymers, metals, and ceramics have propelled toward better alternative composite materials to enhance mechanical and other essential properties; nowadays 3DP research follows a similar direction from neat to composite material (Velu et al., 2019).

3DP filaments infused with carbon nanotubes such as graphene are now commercially available, with the promise to produce conductive and magnetic composites (Al-Hariri et al., 2016; Kwok et al., 2017).

3DP utilizes different techniques for the manufacturing of prototypes, the main techniques include: inkjet printing (IJP); fused deposition modeling (FDM); fabrication with fused filament (FFF); powder-bed fusion (PBD); micro-stereolithography (MSL); dynamic optical projection stereolithography (DOPsL); direct-write assembly (DW); selective laser sintering (SLS); solvent-cast 3DP (SC-3DP); conformal 3DP (C-3DP); two-photon polymerization (TPP); UV-3DP; and stereolithography (SLA); among others (Farahani et al., 2016; Tian et al., 2016).

3DP of polymer nanocomposites (PNCs) with a relatively low amount of layered silicate fillers or conductive nanofillers, such as carbon nanotubes, graphene and metal particles are used to build objects with multifunctional properties having good electrical and thermal conductivity, mechanical strength, and stiffness at relative low cost (Postiglione et al., 2015; Francis & Jain 2016).

In conductive PNCs, the electrical conductivity is governed by electrical percolation, which requires a minimum filler content (volume fraction) to convert an insulating polymer matrix into a conductive composite (Alig et al., 2007). This minimum volume fraction of nanofillers, referred as percolation threshold, strongly depends on factors like, shape and size distribution of the nanofillers (Otten & Van Der Schoot 2009; Gnanasekaran et al., 2014), attractive interactions (Vigolog et al., 2005), and processing methods such as dispersion and agglomeration of nanofillers (Gnanasekaran et al., 2016).

Several studies have been reported on 3DP of conductive PNCs, based on conventionally used 3D printing polymers like poly lactic acid (PLA) and acrylonitrile butadiene styrene (ABS) (Tian et al., 2016; Guo et al., 2015; Rymansaib et al., 2016; Wei et al., 2015). However, the development of new conductive PNC materials for a desktop 3D printer is highly desirable to achieve better printability, mechanical properties and electrical conductivity (Gnanasekaran et al., 2017).

Inside this context, this review study present recent advances towards the application of 3DP technology using conductive and magnetic filaments based on carbon nanostructures embedded in polymer matrix, by showing its main characteristics and also summarizes the producer companies and products available in the market.