The development of new feedstock materials is a central prerequisite for advances in Additive Manufacturing (AM). To increase the breadth of potential applications for 3D and 4D printing of polymers,...
Driven by the rapid development of additive manufacturing technologies and the trend towards mass customization, the development of new feedstock materials has become a key aspect. Additivation of the feedstock with nanoparticles is a possible route for tailoring the feedstock material to the printing process and to modify the properties of the printed parts. This study demonstrates the colloidal additivation of PA12 powder with laser-synthesized carbon nanoparticles at >95% yield, focusing on the dispersion of the nanoparticles on the polymer microparticle surface at nanoparticle loadings below 0.05 vol%. In addition to the descriptors “wt%” and “vol%”, the descriptor “surf%” is discussed for characterizing the quantity and quality of nanoparticle loading based on scanning electron microscopy. The functionalized powders are further characterized by confocal dark field scattering, differential scanning calorimetry, powder rheology measurements (avalanche angle and Hausner ratio), and regarding their processability in laser powder bed fusion (PBF-LB). We find that heterogeneous nucleation is induced even at a nanoparticle loading of just 0.005 vol%. Finally, analysis of the effect of low nanoparticle loadings on the final parts’ microstructure by polarization microscopy shows a nanoparticle loading-dependent change of the dimensions of the lamellar microstructures within the printed part.
Particulate materials
with well-engineered properties are of key
importance for many aspects in our daily life. Polymer powders with
high flowability, for example, play a crucial role in the emerging
field of powder-based additive manufacturing processes. However, the
polymer- and composite material selection for these technologies is
still limited. Here, we demonstrate the design of spherical polymethyl
methacrylate (PMMA) and PMMA–SiO2 composite supraparticle
powders with excellent powder flowability and tailored composition
for powder-based additive manufacturing. Our process assembles these
powders from the bottom up and affords a precise control over surface
roughness and internal morphology via the choice of colloidal primary
particles. We establish process-structure-property relationships connecting
external spray-drying parameters and primary particle sizes with the
resulting supraparticle roughness and, subsequently, with the macroscopic
powder flowability and powder bed density. In a second step, we demonstrate
the control of composition and internal morphology of PMMA–SiO2 composite supraparticles based on different mass mixings
and diameter ratios of the two primary particle dispersions. Finally,
we successfully apply the prepared supraparticle powders in powder
bed additive manufacturing. The optimized flowability of the composite
powders allows the production of two-layered square specimens with
fusion between the individual layers and a uniform and tunable distribution
of nanoscale SiO2 additives without requiring the addition
of any flowing aids.
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