Production of spherical wax and polyolefin microparticles by melt emulsification for additive manufacturing

• Melt emulsification of paraffin, PE and PP granules allows for microparticles.
• Production of spherical polymer particles in a single process step.
• Tailored product properties as function of process conditions (e.g. composition).
• Decreasing temperature and viscosity leads to smaller particles.

Melt emulsification is a top-down approach that so far has been applied in the food industries (cf. homogenization of milk) and in pharmaceutical applications. Within this contribution the applicability of the process for the production of spherical polymer microparticles will be outlined. Size reduction of the polymer raw melt emulsion was realized in a rotor–stator-device. The process is characterized for paraffin and polyethylene (PE) waxes in aqueous environment using Tween 85 as an emulsifier. Process temperature and dispersed phase viscosity have the largest impact on the particle size distribution (PSD): decreasing temperature and viscosity leads to smaller particles. The suitability of the melt emulsification process for technical polymers is demonstrated for polypropylene (PP) emulsified in a continuous hexadecane phase. Polymer particles obtained by the proposed method are promising candidates for advanced powders for additive manufacturing processes like selective laser beam melting (LBM) of polymers. The LBM processability of the obtained PP powders is demonstrated by production of sintered layers.

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