End-capped Polyamide 12: Impact of Powder Bed Fusion-Induced Aging Mechanisms

Laser-based powder bed fusion with polymers (PBF-LB/P) of polyamide 12 (PA12) is an established industrial additive manufacturing technology, where powder reuse is essential for sustainability and reduced costs. This study evaluates PA12 powder with end-capped polymer chains to achieve an improved recycling performance, namely INFINAM® PA 6002 P (Evonik). The material underwent five consecutive processing cycles with 30 % virgin powder replenished after each cycle. Particle morphology, thermal properties, molecular weight evolution, melt flow behavior, and mechanical part performance were analyzed before and after artificial aging. Scanning electron microscopy confirmed stable particle shape and size distribution. Differential scanning calorimetry revealed only minor changes in melting and recrystallization behavior, while size-exclusion chromatography showed significantly lower post-condensation reactivity compared to PA 2200 (EOS), with a stable polydispersity index and a moderate increase in molecular weight. Melt volume rate measurements demonstrated that the initial viscosity as well as the increase upon aging were substantially lower than in PA 2200. Although elongation at break decreased by approximately 5 %, tensile strength and Young's modulus remained stable over the reuse cycles, suggesting that the material maintains structural integrity with only minor shifts in its mechanical profile. Therefore, the inherent stability suggests superior reusability compared to PA 2200, retaining consistent part quality with limited virgin powder addition. While PA 2200 in virgin state exhibits higher ductility, PA 6002 P appears to offer a good balance of strength, reusability, and process consistency. Consequently, PA 6002 P represents a viable, cost-effective, and sustainable alternative for industrial production.