pps proceeding - Abstract Preview
pps proceeding
Symposium: S19 - Additive technology
Oral Presentation
 
 

Modification of polyamide powders and influence on their processability in Selective Laser Sintering

Ruggi David (1)*

(1) INSA - Villeurbanne - France

The SLS process involves almost exclusively semi-crystalline thermoplastic polymer powders. In principle, any semi-crystalline polymer might be used, but the actual range of SLS processable polymers is limited by the complex, and not yet well understood, interactions between the physico-chemical polymer properties in the powder state and the process conditions. As a consequence, the present knowledge and technological boundaries lead to the use of polyamides mainly. Our study focuses on the polyamide type: PA 6 and PA 12. Polyamides are subject to crystal perfection and Solid State Polymerization while they are maintained at high temperature, such as those encountered during the SLS fabrication procedure. The aforementioned phenomena limit the recyclability of the powder and the newly-created part quality, due to increasing viscosity and powder cohesiveness. The present work addresses the evolution of the properties of polyamide powders designed for the SLS process. Based on the SSP phenomena described in the literature , , one can control the crystallinity perfection, the molecular mass and the powder flowability at high temperature by appropriate powder treatment. Indeed, by varying the thermal treatment in different atmospheres, significant evolutions can be observed regarding the molecular weight, melting and crystalline features, and surface aspect. The study of the modifications of the powder/polymer properties provides better understanding of the behavior of such powders in SLS machines, and suggests that a better control over the powder ageing could be beneficial to processability and recyclability. Vouyiouka, Karakatsani, and Papaspyrides, “Solid State Polymerization.” Wiloth, “Über Den Mechanismus Und Die Kinetik Der ε-Caprolactam-Polymerisation in Gegenwart von Wasser. 15. Mitt.”