Mechanical and electrical properties of three-dimensional printed polylactic acid-graphene-carbon nanofiber composites

摘要

The addition of carbon nanofibers (CNFs) and graphene to thermoplastic polymers has the potential to increase the mechanical and electrical properties. The aim of the current study is to investigate the effect of CNF and graphene on the properties of three-dimensional (3D) printed polylactic acid (PLA) samples. The samples are printed using the PLA-graphene-CNF composite filament via fused deposition modeling. As a first objective, composite filament and pure PLA filament characteristics were compared using tensile, scanning electron microscopy and thermogravimetric analysis (TGA) data. Compared with pure PLA filaments, composite filaments revealed an almost 28% reduction in tensile strength due to interfacial defects (poor bonding between PLA and graphene and CNF). Furthermore, 3D printed composite sample properties are compared with 3D printed pure PLA sample using tensile and electrical conductivity data. The 3D printed composite samples also showed less tensile strength (25 MPa) compared with pure PLA 3D samples (37-47 MPa) due to the presence of microvoids. These voids also caused reduction in tensile strength and electrical conductivity of 3D printed composites when compared with the filament properties. The effect of layer orientation was also studied by printing samples at [0 degrees/90 degrees] and [45 degrees/-45 degrees] orientations and found that samples with [45 degrees/-45 degrees] orientation revealed higher elongation (>100%) and lower electrical conductivity. It is observed that the presence of graphene and lack of bonding between PLA and CNF resulted in the improper fusion of the printed layers, which led to a decrease in tensile strength and electrical conductivity but an increase in toughness.