Comparison of structural health assessment capabilities in epoxy - Carbon black and epoxy - Carbon nanotube nanocomposites

Abstract

A novel method for comparing structural health of different types of brittle epoxy nanocomposites filled with carbon nanostructured fillers is presented. Epoxy - 0.2 vol% carbon black (CB) and epoxy - 0.2 vol% carbon nanotube (CNT) nanocomposite bars were prepared by calendering and thermal curing. Nanocomposite bars were subjected to Vickers diamond indentation to produce sub-surface damage. Electrical conductivities were analysed by 4-point method to estimate the structural damage caused by indentation. For comprehensive comparison, fracture toughness and percolation threshold were analysed as well. Because of the systematically induced indentation damage, a sharp decrease of 89% was observed in the electrical conductivity of epoxy - CNT nanocomposite as compared to 25% in the electrical conductivity of epoxy - CB nanocomposite. CNTs impart superior damage sensing capability in brittle nanocomposite structures, in comparison to CB, due to their high aspect ratio (fibrous nature) and high electrical conductivity. BME-PT.