Investigation on the recycling potential of additively manufactured carbon fiber reinforced PA 6.6

• An effective method of recycling short carbon fiber reinforced polyamide 6.6 by additive manufacturing is presented. • An extensive mechanical evaluation was carried out on the material system for the juvenile filament, the support structure material, the purge line material, as well as for the recycled filament. • The evaluation aims to assess the impact of multiple recycling cycles and gives results for the mechanical properties after recycling Carbon fiber reinforced polymers (CFRP) are already used in a wide range of applications such as automotive, aerospace and renewable energy industries and demand on this material class is increasing steadily. As demand increases, the amount of CFRP waste, either from production or at the end of life of components, increases simultaneously and sustainable solutions such as disposal, reuse or recycling of fiber reinforced materials getting more and more important. In this paper one possibility for recycling short carbon fiber reinforced polyamide 6.6 (CF/PA 6.6) is presented. The recycling process includes shredding of the material, drying and filament extrusion to enable a reuse of the material with an additive manufacturing process. The focus of this investigation is on the mechanical properties of the recycled filaments itself as well as on the 3D printed specimen considered recycled filaments. The properties at different stages of the short carbon fiber reinforced polyamide 6.6 recycling process were investigated, including the juvenile CF/PA 6.6 as well as specimens made from one- or two-times recycled material. Mechanical performance was evaluated by tensile, bending and impact testing. Experimental results pointed out that no significant difference in performance of juvenile and recycled materials was observed for tensile and flexural loads. The impact strength of the recycled specimen decreased to a small extent.