Expanding polymeric feedstocks for powder bed fusion via rational control of liquid–liquid phase separation

Abstract

AbstractPowder bed fusion (PBF) is a promising technology in polymeric additive manufacturing, whose growth is inhibited by limited material options. In this manuscript, we report the use of thermally induced phase separation (TIPS) to controllably produce polymer powders of polypropylene that are suitable for PBF. Moreover, these studies provide crucial insight into the factors that govern the final size of the produced powder, offering fundamental insight that fosters the rational control of powder fabrication for PBF. More precisely, the impact of polymer concentration, molecular weight, and quench temperature on the size of the powder is demonstrated, where the particle size increases with solution concentration, quench temperature and molecular weight. The molecular weight dependence is consistent with a decrease in polymer solubility with an increase in chain length, while the solution concentration dependence can be explained by the relative fractions of the two phases in the precipitation process of polymer solutions. Careful analysis of the temperature and solution concentration dependence of the powder verifies that droplet coalescence is the governing mechanism in the phase separation‐based particle formation process. Therefore, this fundamental understanding provides pathways to use TIPS to produce powders suitable for PBF from a broad range of polymer solutions.