Formation of spherical micron-sized polyamide particles for additive manufacturing via liquid-liquid phase separation

Abstract

Selective laser sintering (SLS) is an additive manufacturing (AM) process that yields excellent part qualities with good mechanical properties. The SLS process employs micron-sized polymer particles, which are selectively fused by a laser. While there seem to be hardly any boundaries regarding design, there are quite some restrictions concerning the variety of commercially available SLS materials. With a market share of roughly 90%, polyamide 12 (PA12) is currently the most widely used polymer material for SLS. In order to increase the understanding of the precipitation based manufacturing process for polyamide powders, production of polyamide 11 powders via precipitation in ethanol was investigated. The polymer particles need to be optimized regarding size, shape, flowability and packing characteristics. In this contribution particle manufacturing via liquid-liquid phase separation is discussed. Bulk polymer material of polyamide 11 is directly converted to spherical micron sized particles in a single unit operation. The produced particles are characterized regarding their size and morphology. Furthermore, also structural characteristics, crystallinity and flowability are analyzed and the product properties are correlated with process parameters. We discuss the potential of this process for the production of novel, easy-to-handle polymer particle systems for SLS.