Graphene and Carbon Nanotube PLA Composite Feedstock Development for Fused Deposition Modeling

Abstract

Additive manufacturing shows significant potential for replacement of traditionally manufactured parts, part repair, and prototype development due to complexity of allowable part geometry and low raw material usage, however mechanical properties of parts processed through additive typically suffer in comparison. To address this decrease in properties, the goal of this study will be to develop an improved and sustainable feedstock material for fused deposition modeling through reinforcement of polylactic acid with graphene and multiwalled carbon nanotubes. Composites with loadings of 0.5, 0.2, and 0.1 wt% of each reinforcement were extruded to form filament feedstock for fused deposition modeling, and tensile and impact specimens were printed using a Lulzbot Mini according to ASTM D638 and D256. Mechanical properties were evaluated through tensile and impact testing, while fracture surfaces were analyzed using a scanning electron microscope. The thermal properties of the feedstock material and postprinted material were analyzed with differential scanning calorimetry. Reinforcements led to a moderate increase in mechanical properties with the 0.2 wt% loading of graphene showing a 47% increase in tensile strength, a 17% increase in modulus, and 12% increase in energy absorbed upon fracture. The 0.1 wt% loading of MWCNT had respective increases of 41%, 16%, and 9%, with all reinforcement loadings leading to no statistically significant change in the thermal properties or fracture behavior.