Interlaminar properties of carbon nanotubes modified carbon fibre fabric reinforced polyimide composites

Carbon fibre reinforced polymers are widely used in industrial applications due to their excellent properties. However, the weak matrix-dominated interlaminar properties limit its further application. With their unique properties, carbon nanotubes (CNTs) have great potential to improve the mechanical properties of composite materials. In this paper, carbon nanotube-modified carbon fibre/polyimide (CF/CNTs/PI) multi-scale composites were prepared by introducing amino-functionalized multi-walled CNTs into a PI resin matrix using an ultrasonic dispersion method. The interlaminar properties of the prepared composites were comprehensively evaluated by double cantilever beam (DCB), end-notched flexure (ENF), and short seam shear (SBS) tests. It is shown that the addition of 0.5wt.% CNTs increased the Mode I and Mode II interlaminar fracture toughness of the material by 50.21% and 61.74%, respectively, and the interlaminar shear strength (ILSS) by 42.85%. The CNTs bridging the crack tip and enhancing the fibre/matrix interface bonding ability were the dominating mechanisms for the improvement of interlaminar properties.