Radiation spheroidization as a potential method enabling recycling of polyamide 12 waste from powder bed fusion of polymers

• Radiation spheroidization has potential to become a recycling method for PBF waste. • Processing of aged PA12 by radiation spheroidization has been demonstrated. • Spherical or near spherical particles can be obtained by controlled remelting. • Spheroidization improves bulk density, flowability and viscosity of PA12 powder. • The capabilities and limitations of radiation spheroidization were discussed. Thermal aging hinders the use of powder bed fusion (PBF) for large-scale production. Inefficient waste management in PBF requires mixing 30–50 % virgin powder, while only ∼ 10 % becomes final parts. In this study, a novel method of polymer powder processing is used − radiation spheroidization (RS). In this process, a powder is continuously dispersed in a gas stream, forming an aerosol. This aerosol is subsequently irradiated with an infrared spectrum, causing the particles, which are at near-freefall conditions, to melt, and ultimately results in a change in their shape. Polyamide 12 (PA12) powder was evaluated in three conditions: virgin, thermally aged and spheroidized. Technological properties of spheroidized PA12 reveals spherical or near-spherical shaped particles with enhanced bulk density, flowability and melt viscosity. Moreover, changes in crystalline structure, from α- to γ-phase. With additional thermal processing of aged PA12, progressive thermal aging and degradation of the polymer is observed via gel permeation chromatography. Although additional thermal processing can affect the functional properties of PBF parts, the spheroidization process of PA12 as an RS method itself can be optimized. Therefore, we believe that RS has the potential to become another material-driven method of recycling PBF waste.