Effect of MWCNTs on mechanical properties of carbon fiber non-crimp fabric/epoxy laminates

MWCNTs were functionalized with carboxyl and then mixed with epoxy TDE85. The obtained mixtures were used to impregnate the NCF laminates, stacking with a sequence of 0°/90°/+45°/-45°_S. Flexural properties, interlaminar shear strength (ILSS), and mode Ⅱ interlaminar fracture toughness (G_ⅡC), as well as the glass transition temperature (T_g) of the resulting laminates were characterized using three-point bending, short beam shear, end-notch flexure (ENF) specimens, and a dynamic mechanical analysis, respectively. SEM was used to analyze the fracture characteristics of the tested ENF specimens. The results show that there are reinforcing effects of the MWCNTs on the mechanical properties when the mass fraction of the MWCNTs varies from 0 to 2.0%. The flexural strength and modulus are improved by 26% and 6%, respectively, with 2.0% mass fraction of MWCNTs. The ILSS, G_ⅡC and T_g are enhanced by 14%, 27% and 14%, respectively when 0.5% mass fraction of MWCNTs is used.