A facile method for improving interlayer adhesion of polyamide 6/carbon fiber composites for fused filament fabrication

Abstract The challenge for fused filament fabrication (FFF) parts is the anisotropy of their mechanical properties. Lightweight and high‐strength carbon fiber reinforced polymers (CFRPs) exhibit weaker interlayer bonding strength (characterized by Z‐axis tensile strength) when formed using FFF compared to their neat polymers. In order to improve the interlayer bonding strength of polyamide 6 (PA6)‐based CFRP printed parts, polyamide 6 and polyethylene terephthalate (PET) were blended to produce FFF filaments in this work. The mechanical properties, cross‐sectional morphology, and thermal properties of the 3D‐printed parts of each filament were tested. It was found that when the PA6/PET mass ratio was 90/10, the Z ‐axis tensile strength was 27.4 MPa, which was 94.3% higher than that of the carbon fiber‐reinforced PA6‐based composite without PET. The interlayer bonding strength has been effectively improved while maintaining the material strength (characterized by X ‐axis tensile strength), and there is no need to improve the printer or perform post‐processing, reducing processing costs. The improvement of interlayer bonding enhances the sealing and chemical corrosion resistance of printed parts, providing new material options for the expansion of FFF application fields. Highlights Short carbon fiber‐reinforced PA/PET filaments for FFF were prepared. The addition of PET reduced the moisture absorption rate of the blends. PET reduced the viscosity of the blends. The interlayer bonding strength of CFRP has increased by 94.3%. When the PET ratio was 10 wt%, the comprehensive properties were optimal.