Effects of Optimized Thermal Annealing on the Microstructure and Mechanical Property of FDM-Printed PA6/CF Composites

Fused Deposition Modeling (FDM) is a widely used 3D printing method that forms parts by extruding thermoplastic materials through a heated nozzle. It offers advantages such as design flexibility and mold free fabrication of complex structures. Polyamide (PA), known for its excellent wear and heat resistance, is widely used in FDM due to its good processability. However, PA parts produced by FDM exhibit weak interlayer bonding due to the layer by layer deposition process, resulting in poor mechanical performance. Conventionally molded PA exhibits a tensile strength of approximately 100 MPa, whereas FDM printed PA parts typically exhibit lower values, thereby limiting their industrial applicability. This study proposes a facile annealing treatment method to enhance the interlayer adhesion and mechanical properties of FDM printed PA6 composites. By optimizing annealing temperature and time, the bulk mechanical properties were remarkably enhanced. The maximum tensile and flexural strengths reached 78.1 MPa and 90.5 MPa, respectively, while Young's modulus more than doubled (up to 2.63 GPa).