Powder Bed Fusion (PBF) is an important process in polymeric additive manufacturing. However, there exist limited polymers available for PBF, where most efforts use nylon. We will discuss ongoing research in our group to understand and control the rational development of scalable processing protocols that use liquid-liquid phase separation (LLPS) to reproducibly fabricate polymer powders that are suitable for powder bed fusion from polymers in the waste stream. In this process, the solvent quality of a polymer solution is reduced by a temperature quench or addition of non-solvent, causing the polymer to precipitate via phase separation. This results in the formation of polymer particles suitable for PBF that can be easily recovered, which also enables reclamation and <i>reuse</i> of solvent. Understanding the fundamental driving forces that guide the variation of final particle size with polymer solution concentration, polymer crystallinity, solvent type, and quench temperature provides pathways to rationally control the size and manufacturability of the final particles.<br/>This process has been used in our group to create powders that are suitable for PBF from products in the waste stream including polypropylene pill bottles, polyethylene terephthalate water bottles, high density polyethylene milk jugs, and low density polyethylene sandwich bags. The process of powder formation is driven by the phase separation of polymer solutions, which involves spinodal decomposition followed by Ostwald ripening and droplet coalescence. Control of powder formation requires understanding which of these processes regulates particle size in the precipitation process. We will discuss results that determine the impact of temperature, solution concentration, and molecular weight on formed particle size and offer important fundamental understanding into the phase separation processes that govern particle formation. This in turn offers insight that will enable the rational design of thermodynamic conditions required to create polymer powders that are suitable for powder bed fusion for a broad range of polymers from the waste stream using the LLPS process.

Understanding innovative solution processing to enable the use of recycled polymers in additive manufacturing

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.