Polymer composites for damage-sensing applications

With the advent of carbon-based nanomaterials, there has been great interest in the recent past in the use of carbon nanotubes (CNTs) for damage-sensing applications of polymer composites. Well-dispersed carbon nanotubes, even at lower weight concentrations, generate an excellent electrically conductive network in polymers. The change in the electrically conductive network in the polymer composites under various kinds of mechanical loads can be determined from piezoresistive measurements. In this chapter, the damage-sensing capabilities of CNT-embedded epoxy under various quasistatic mechanical loading conditions are presented. To disperse CNTs in the two-part thermoset epoxy matrix, shear mixing and ultrasonication processes are employed. Piezoresistance is determined using four circumferential probe measurement systems, in which a constant current is supplied through outer probes and voltage is measured from inner probes. The effect of various loading conditions on the piezoresistance change in the composites is determined and later it is correlated to deformation and damage mechanisms inside the composites.