Effect of graphene nanoplatelets and multiwalled carbon nanotubes on the viscous and viscoelastic properties and printability of polylactide nanocomposites

Linear and non-linear viscoelasticity, relaxation behavior steady shear viscosity of polylactide (PLA) nanocomposites filled with 1.5–9 wt.% graphene nanoplatelets (GNPs) multiwall carbon nanotubes (MWCNTs) are studied to gain control on printability. Results show strongly increased rheological characteristics, good dispersion, small fractal size very low percolation threshold MWCNTs in PLA, limited printability at 9 filler content. This is associated strong particle-particle polymer-particle interactions MWCNT/PLA due the large surface area, needle shape functionalization MWCNT. In contrast, a significant lubrication effect non-functionalized GNPs observed hydrodynamic slip alignment flow direction, which facilitated Based computer fluid dynamics modeling, an “elastic turbulence” phenomenon, as plug nanocomposite melt observed, cause clogging nozzle. The decrease wall viscosity, drag force coefficient, elastic number (Weissenberg Reynolds numbers), lubricant nozzle wall. increase parameters resist flow. Numerical simulations rates corresponding steady-shear viscosities “printing window” near found be agreement experimental results. main characteristics numerical that filament determined. These findings will contribute development optimization novel printable materials anisotropic fillers.