Enhancing interfacial performance and fracture toughness of carbon fibre reinforced thermoplastic composites

• Hybrid toughening with PDA, MWCNTs, and PPS veil improved mechanical properties. • Significant enhancements in Mode I interlaminar fracture resistance were observed. • PPS pull-out, and fibre bridging were key toughening mechanisms. • Surface treatments improved adhesion, flexural, and interlaminar shear strength. • Microstructural analysis showed changes in functional groups and surface morphology. Enhancing the interlaminar fracture toughness of composites significantly improves their load bearing capacity and structural integrity over longer service life by improving their resistance to delamination. The effect of hybrid toughening of Elium-based thermoplastic composites involving polydopamine (PDA), multi-walled carbon nanotubes (MWCNTs) sizing, and polyphenylene sulfide (PPS) veil interlayers was investigated to observe the mechanical response using 3-point bending, interlaminar shear strength, and Mode I fracture toughness tests. The enhancement of fibre–matrix adhesion contributed to improvements in both flexural strength and interlaminar shear strength, while additional toughening mechanisms, such as PDA bridging, PPS pull-out and breakage, and fibre bridging, enhanced the Mode I interlaminar fracture toughness by 218%.