Towards developing advanced CFRP with simultaneously enhanced fracture toughness and in‐plane properties via interleaving CNT/PEI hybrid veils.

Highlights Carbon nanotube (CNT)‐polyetherimide (PEI) hybrid nanofibrous veils were prepared through the electrospinning process to function as an interlayer in carbon fiber reinforced polymer composites (CFRP), and the effects of the addition of the hybrid fiber veils on the interlaminar fracture properties and flexural properties of CFRP were investigated. The results showed that interleaving CNT/PEI hybrid veils can effectively avoid long‐troubled trade‐off between mode‐I interlaminar fracture toughness and in‐plane properties when using thermoplastic toughening materials. Specifically, the GIc value and flexural strength of the laminates were increased by as much as 86.2% and 14.3%, respectively when CNT content was reached up to 0.7 wt% in CNT/PEI hybrid veil. This method adopts ultra‐low PEI and CNT additions, and the limited quantity of these additives demonstrates a notably high interlaminar toughening efficiency while concurrently enhancing the strength, rendering it a promising strategy for both toughening and strengthening. PEI is used as a carrier to transport CNT to the CFRP interlaminar layers. PEI‐CNT hybrid fiber veils improve GIC and flexural strength of CFRP. PEI‐CNT hybrid fiber veils impede crack expansion through various mechanisms. This method adopts ultra‐low PEI and CNT additions. [ABSTRACT FROM AUTHOR]