The effects of carbon nanotube reinforcement on adhesive joints for naval applications

Abstract

The adhesive joint strength of various carbon fiber composite and steel joints was studied using Mode II fracture strength testing. The effect of the addition of multi-walled carbon nanotubes (MWNTs) to the adhesive was also studied. The effects of the MWNTs' diameter, length, concentration and functional group were also investigated. It was demonstrated that an adhesive joint with greater strength than a similarly constructed scarf joint can be created. It was further shown that the addition of MWNTs to the adhesive increased the Mode II fracture strength of the adhesive for a steelcomposite and composite-composite joints. It was also shown that the fracture path shifted from through the adhesive when no nanotubes were present to between the adhesive and metal or composite interface with the addition of nanotubes. The concentration, diameter, length and functionalization of the MWNTs added to the adhesive played a significant role in the strength of the joint. Not all nanotubes improved joint strength. Finally, it was determined that the distribution of the MWNTs in the adhesives impacted the ultimate strength of the bond. The functionalization of the nanotubes with a carboxyl group improved nanotube distribution in the adhesive and show significant promise for further improving the joint strength.