Optimal Carbon Fiber Content and Annealing Strategy for High‐Performance FDM ‐Printed CF / PET Co

ABSTRACT

Fused deposition modeling (FDM) of high‐performance thermoplastics is limited by the trade‐off between mechanical reinforcement and processability. Here, we address this gap by investigating the influence of short carbon fiber (SCF) content (5–20 wt%) on FDM‐printed PET composites, with linear low‐density polyethylene (LLDPE) and polyethylene grafted with maleic anhydride (PE‐g‐MA) incorporated to enhance toughness and interfacial compatibility. Rheological analysis indicates that an increase in CF content markedly enhances both the storage modulus and melt strength. Differential scanning calorimetry (DSC) analysis reveals a significant heterogeneous nucleation effect induced by CF. Micro‐morphological assessments confirm uniform fiber distribution and robust interfacial adhesion at 15 wt% CF, whereas fiber agglomeration and more defects emerged at 20 wt% CF. Mechanical testing demonstrates that tensile strength, elastic modulus, and notched impact strength peak at 15 wt% CF, achieving increases of 92%, 283%, and 115%, respectively, relative to the matrix without CF. Notably, a post‐printing annealing treatment further improves tensile strength by 18.1% and heat deflection temperature (HDT) by 146.7%. These results establish that 15 wt% CF is the optimal formulation for balancing processability and performance, providing a practical and scalable pathway for manufacturing high‐performance carbon fiber reinforced polyethylene terephthalate (CF/PET) composites via FDM.