Preparation of carbon black/graphene nanosheets/PP composites with 3D separated conductive networks based on selective laser sintering

Abstract

The main research goal of high-performance conductive polymer composites is to improve electrical conductivity and reduce the percolation threshold.Designing an effective conductive network is one of the fundamental ways to improve the conductivity. In this study, polypropylene composite powders coated with carbon black (CB) and graphene nanosheets (GNSs) were prepared by a combination of ultrasonic dispersion and liquid-phase deposition, and sintered using a selective laser sintering process to prepare polypropylene composites with three-dimensional separated conductive networks. The synergistic effect of binary compound fillers of CB and GNSs was utilized to further improve the electrical conductivity of the composites. When the filler loading was 2% and the ratio of CB to graphene was 7:3, the electrical conductivity of the polypropylene composite was 1.315 Â 10 À3 S/m, which was eight orders of magnitude higher than that of pure polypropylene. In addition, the tensile strength and elongation at break of CB/GNSs/PP composites were improved by 36.4% and 20.77% with excellent mechanical properties. The effects of fillers on the SLS process, thermal stability, melting, and crystallization behavior of the composites were investigated. This study provides an effective and feasible strategy for the preparation of high-performance conductive polymer composites using SLS 3D printing process.

3D Printed Graphene and Graphene/Polymer Composites for Multifunctional Applications

“…Depending on the specific material, additional post-processing steps may be required, such as heat treatment, surface finishing, or infiltration with polymers or metals to improve the strength or surface characteristics. [12], (b) Typical fabrication process of graphene/polymer powders for SLS-based 3D printing [115], (c,d) SLS integrated with simultaneous LIG for 3D printing of neat graphene objects [116], (e) Transmission electron microscopic [117] and (f) scanning electron microscopic images [118] showing microstructures of SLS printed graphene/polymer composites.…”

“…After ultrasonication and mechanical stirring, the resultant suspension was filtrated using a funnel to obtain uniform GO-coated PVDF composite powders for SLS, as shown in Figure 7 b [ 115 ]. Graphene/carbon black/polymer composite powders were also prepared using similar ultrasonic dispersion-assisted liquid deposition, where graphene nanosheets and carbon black were dispersed in organic solvents using ultrasonication before the addition of polymer powders [ 118 , 119 ]. More environmentally friendly aqueous systems were used for in situ reduction of GO sheets with the existence of polymer powders, obtaining rGO-coated composites powders [ 120 ].…”

“…More environmentally friendly aqueous systems were used for in situ reduction of GO sheets with the existence of polymer powders, obtaining rGO-coated composites powders [ 120 ]. As graphene-coated polymer spherical powders are applied in the SLS process, the graphene mainly locates among interfaces of the polymer granules, providing electrically conductive percolations and mechanical reinforcements [ 117 , 118 , 119 , 121 ]. Solid fabrication of graphene/polymer SLS powders without involving solvents is also applicable.…”

“…As shown in Figure 7 e, the transmission electron microscopic images of SLS-printed graphene/thermoplastic polyurethane (TPU) composites clearly demonstrated that the surfaces of TPU particles was covered by graphene sheets, forming a 3D segregated network [ 117 ]. Shen et al [ 118 ] revealed the effect of graphene content on the segregated distribution. With a larger graphene content, the distance between adjacent polypropylene particles increased, showing wider graphene-rich regions ( Figure 7 f).…”

“… ( a ) Schematic illustration of apparatus [ 12 ], ( b ) Typical fabrication process of graphene/polymer powders for SLS-based 3D printing [ 115 ], ( c , d ) SLS integrated with simultaneous LIG for 3D printing of neat graphene objects [ 116 ], ( e ) Transmission electron microscopic [ 117 ] and ( f ) scanning electron microscopic images [ 118 ] showing microstructures of SLS printed graphene/polymer composites. …”