<p>Powder recycling in laser powder bed fusion (PBF-LB) of thermoplastic polyurethane (TPU) offers economic and environmental benefits, but introduces challenges related to thermal aging and its impact on part quality. This study presents a comprehensive evaluation of TPU 1301 powder degradation across successive build cycles without refresh, and integrates morphological, rheological, thermal, and mechanical analyses to establish a coherent qualitative framework for understanding the reduced consolidation quality and mechanical performance observed in parts produced from aged powder. In the present work, aging across 8 build cycles led to a 17.5% increase in median particle size (D50), a 22% decrease in bulk powder density (BD), and a 35% increase in particle cohesion. A thermal analysis revealed a 14% increase in crystallinity and a 28% decrease in the melt flow rate (MFR), the latter indicating a reduced molecular weight and increased chain mobility. These changes directly affected the quality of built parts, which saw a 12% density decrease and a 38% surface roughness increase. Mechanical tests also manifested a 15% decrease in Shore A hardness and 26–30% drop in quasi-static tensile and compression resistance, while dynamic impact testing revealed sharper acceleration peaks and shorter time-to-peak values, indicating a decrease in the energy absorption capacity. These findings establish a direct link between powder aging and part performance in PBF-LB elastomers. They highlight the need for integrated powder‑ and part‑level quality control strategies, particularly for elastomeric lattices where consolidation quality and surface integrity critically influence the mechanical response.</p>