Improving through-thickness conductivity of carbon fiber reinforced polymer using carbon nanotube/polyethylenimine at the interlaminar region

The through-thickness conductivity of carbon fiber reinforced polymer (CFRP)composite was increased by incorporating multiwalled carbon nanotubes inthe interlaminar region. Carbon nanotubes (CNTs) were dispersed in a poly-ethylenimine (PEI) binder, which was then coated onto the carbon fiber fabric.Standard vacuum-assisted resin infusion process was applied to fabricate thecomposite laminates. This modification technique aims to enhance the electri-cal conductivity in through-thickness direction for the purpose of nondestruc-tive testing, damage detection, and electromagnetic interference shielding.CNT concentrations ranging from 0 to 0.75 wt% were used and compared topristine CFRP samples (reference). The through-thickness conductivity of theCFRP exhibited an improvement of up to 781% by adopting this technique.However, the dispersion of CNT in PEI led to a viscosity increase and poorwetting properties which resulted in the formation of voids/defects, poor adhe-sion (as shown in scanning electron micrographs) and the deterioration of themechanical properties as manifested by interlaminar shear strength anddynamic mechanical analysis measurements