Inter-Laminar Mechanical Properties Improvements in Carbon Nanotubes Reinforced Laminated Nanocomposites

Owing to their superior mechanical properties, carbon nanotubes (CNTs) can be used as an additional reinforcement to improve the mechanical properties of laminated composite materials. To incorporate the excellent properties of CNTs into the existing traditional composite technology, vertically aligned high density arrays of CNTs were grown perpendicular to the surface of 2-D woven cloths and tows of various fibrous materials. The nano-forest like structures of fabrics is used to fabricate 3-D reinforced nanocomposites. Due to the presence of aligned CNTs in through-the-thickness direction, it is expected that the inter-laminar and through-the-thickness properties of the composite laminate will be improved considerably. To demonstrate the effectiveness of our approach, various composite single lap-joint specimens were fabricated for inter-laminar shear strength testing. Carbon woven cloths with and without CNTs nano-forests were inserted in between the single lap-joints using epoxy adhesive to measure the interlaminar shear strength improvements due to the presence of through-the-thickness aligned CNTs nano-forests. It is observed that single lap-joints with carbon cloth insertion layers having CNTs nano-forest can carry up to 12% higher shear stress and 16% higher strain-to-failure. The failures of samples with nano-forests were completely cohesive while the sample with carbon woven cloth insertion failed adhesively. This concludes that the adhesion of adjacent carbon fabric layers can be considerably improved due to the growth of vertically aligned CNTs nano-forest in through-the-thickness direction.