Enhanced mechanical performance of 3D printed continuous carbon fibre reinforced polyphenylene sulphide composites through dopamine treatment and post-processing compression

This study investigates the impact of dopamine-treated carbon fibre reinforcement and post-processing techniques in polyphenylene sulphide (PPS) composites, with a focus on improving interfacial and interlayer properties. The synergistic effects of continuous carbon fibre (CCF) treatment with polydopamine/silica nanoparticles (PDA/NPs) and post-processing on the mechanical performance of 3D printed composites are explored. The findings demonstrate that treated composites exhibit significant improvements in interlaminar properties, with increases in flexural strength by 27% and interlaminar shear strength (ILSS) by 172%, compared to untreated specimens. Molecular dynamics (MD) simulations and nano-indentation tests reveal the mechanisms behind the improved fibre/matrix interfacial adhesion attributing to PDA/NPs network on the fibre. Differential scanning calorimetry (DSC) and microscopic analyses are utilised to assess enhancements in crystallinity, void content, and fibre orientation after post-processing. Furthermore, we introduce a novel post-processing method involving a salt bath, which aligns with the unique advantages offered by 3D-printed complex composites. This approach is validated with two complex demonstrative geometries, confirming its effectiveness in maintaining structural integrity while enhancing interlayer properties. The integration of pre-processing with the PDA/NPs network and post-processing techniques with a salt bath offers particular benefits for additively manufactured high-performance materials.