Effects of plasma modified carbon nanotube interlaminar coating on crack propagation in glass epoxy composites

Fibre reinforced pre-preg systems have very good in plane properties, however they are weak in their through thickness (z) direction. This research aims to address this issue by adding plasma treated carbon nanotubes (CNTs) between the prepreg plies using a simple drawdown coating procedure. The significant test result shows by coating carbon nanotubes with a relatively low areal density (1.2 g/m2) the propagation mode I toughness can be improved by up to 46%. Crack deviation leading to increased glass fibre bridging was observed for lower CNT coating concentrations explaining the improved performance. However at the highest areal coating density (2.0 g/m2) fibre bridging disappeared and a stick-slip crack response was observed resulting in lower delamination resistance. This research demonstrates a simple method to incorporate a nanointerlayer that can manipulate crack propagation, leading to increased delamination resistance.