3D Printing of Mechanical Recycled PA12/CF Composite

The management of small volumes of polymer and composite waste poses a major challenge for the polymer processing industry because standard recycling plants rely on a continuous, high-volume flow of sorted materials to run. Additive Manufacturing (AM) offers high potential to reprocess small volumes by turning the waste into usable filaments. Although carbon fiber-reinforced polyamide (PA/CF) composites are widely used in engineering applications, comprehensive experimental studies are needed to assess how the end-use properties are retained when recycled PA/CF composites are processed by AM. This study investigates the feasibility of recycling and remanufacturing PA12/CF waste using Fused Filament Fabrication (FFF). The mechanically recycled PA12/CF composite was extruded into filament and 3D printed under different configurations. The physical, chemical, thermal, rheological, microstructural, and mechanical properties of the recycled PA12/CF (rPA12/CF) composite were systematically investigated and compared with those of the virgin counterparts. Experimental results indicated that the recycled PA12/CF composite exhibited very good chemical and thermal stability. However, the mechanical recycling process led to a decrease in the mean CF length, from 0.203 mm in vPA12/CF to 0.147 mm in rPA12/CF, as well as a reduction in melt shear viscosity. The mechanical properties of the rPA12/CF composite depend on the printing configuration. The rPA12/CF samples printed at 0° orientation retained at least 90% of the elastic modulus or bending modulus values of the vPA12/CF counterpart, while the tensile strength and ductility increased by 10%. This study confirms the potential of FFF technology to reprocess small volumes of recycled composite waste into specialized parts where the balance between the cost and end-use properties justifies the use of recycled materials.