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Journal of Polymer & Composites Original Research Special issue

Analysis of Ageing and Degradation Behavior of Polyamide-12 for Sustainable Additive Manufacturing

  1. G. Venkata Nagamani Department of Mechanical Engineering, Koneru Lakshmaiah Education Foundation, Vaddeswaram
  2. Sri Harsha Arigela Department of Mechanical Engineering, Koneru Lakshmaiah Education Foundation, Vaddeswaram

Abstract

Additive Manufacturing (AM), particularly High-Speed Sintering (HSS), has emerged as a transformative technology capable of producing complex thermoplastic parts with high efficiency and minimal material waste. The HSS process involves selective deposition of radiation-absorbing ink followed by infrared heating to consolidate polymer powders-most commonly polyamide-12 (PA12). While PA12 is widely used due to its excellent thermal stability and mechanical properties, the sustainability of HSS strongly depends on the reuse of unsintered powder. Recycled powder is subjected to repeated thermal exposure during successive build cycles, which induces ageing and degradation. However, systematic studies on the influence of powder ageing in HSS remain limited. This work investigates the degradation behavior of PA12 across three recycling iterations without refreshing. Powder and part qualities were evaluated using Scanning Electron Microscopy (SEM) for morphological changes, Melt Volume Rate (MVR) for rheological behavior, and Differential Scanning Calorimetry (DSC) for thermal transitions. Additional mechanical testing provided insight into strength retention and ductility. Results indicate progressive increases in crystallinity and melt enthalpy, accompanied by reduced bulk density, particle agglomeration, and a noticeable decline in ultimate tensile strength and elongation at break with each iteration. Thermogravimetric Analysis (TGA) further confirmed changes in thermal stability of aged powders. The findings demonstrate that powder ageing exerts a direct and significant influence on part performance in HSS. Specifically, R3 powder retained properties closer to virgin PA12, while R2 powder showed marked degradation. These results provide valuable guidance for optimizing refresh ratios and designing sustainable job boxes, thereby reducing waste and ensuring reliable part quality. Overall, the study contributes to sustainable additive manufacturing by establishing performance thresholds for PA12 powder reuse in HSS.

Keywords

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