Fracture response of adhesive joints reinforced with aligned multi-walled carbon nanotubes using an external electric field

This paper aims to study the effect of aligning multi-walled carbon nanotubes (MWCNTs) on the fracture behavior of adhesively bonded joints experimentally and numerically. MWCNTs were aligned in the adhesive thickness direction using a direct current electric field. Mode-I facture behavior of adhesive joints were studied by testing double cantilever beam (DCB) specimens manufactured using the neat and reinforced adhesives with randomly dispersed and aligned MWCNTs. The maximum improvements in the fracture energy obtained by reinforcing the adhesive layer with randomly dispersed and aligned MWCNTs were 135% and 160%, respectively, at 0.3 wt% of nanofillers. Moreover, the maximum load of adhesive joints was improved maximum by about 55% and 88% by the addition of 0.3 wt% randomly dispersed and aligned MWCNTs, respectively. The SEM fractography showed more contribution of aligned MWCNTs in the load bearing capacity and fracture resistance of adhesive joints by promoting the reinforcing mechanisms of nanotube pull-out and debonding. Furthermore, fracture behavior of adhesive joints was modeled with cohesive zone model calibrated by a compliance-based direct method.