A Comprehensive Investigation of the Mechanical Properties of Resin‐Infused 3D ‐Printed CF ‐ PETG Composites

ABSTRACT The post‐processing of 3D‐printed polymers is promising in the potential enhancement of the mechanical properties of porous components. However, the scant research on comprehensive understanding about the influence of infill density and pattern on resin infiltration efficiency and the consequent mechanical performance in epoxy‐filled carbon fiber‐reinforced poly(ethylene terephthalate)‐glycol (CF‐PETG) structures provides a significant research gap. To fill this gap, this study presents the post‐3D‐printing property enhancement of the CF‐PETG component via epoxy filling. The process starts with the additive manufacturing of CF‐PETG components with different infill patterns (cubic, trihexagonal, and gyroid) and then fills the printed voids with epoxy resin to enhance their mechanical attributes. Three different infill densities (20%, 35%, and 50%) were considered for each of the cubic (CU20, CU35, CU50), trihexagonal (TH20, TH35, TH50), and gyroid patterns (GY20, GY35, GY50), resulting in a total of nine types of specimens. The highest compressive strength (60 MPa) and specific compressive strength (13 MPa/g) were achieved for the TH35 specimen. The same specimen showed the highest specific flexural strength (7.6 MPa/g) and stiffness (2.4 kN/mm) as well. The specific energy absorption (SEA) assessment revealed that CU20 exhibits the best SEA value of 1.4 × 10 ⁻² kJ/g. The highest fracture toughness of 2.6 MPam ^1/2 was shown by TH35. These findings underscore the significance of standardizing infill density and pattern in efficient resin distribution in 3D‐printed polymer composites.