Strain and Damage Sensing in Polymer Composites and Nanocomposites with Conducting Fillers

In polymer composites and nanocomposites with conducting fillers, conductivity changes significantly with strain and with the evolution of damage, which forms the basis for using the composite itself as sensor (self-sensing) for strain and for structural health monitoring. Less frequent is the use of capacitance sensors, where the changes of capacitance of the sample during deformation are utilized. Here we present results of recent work in the use of electrical dc measurements to monitor strain and to follow the onset and evolution of damage in selected examples of polymer composites and nanocomposites, pointing out differences in their properties. The materials we measured were PP (Poly-Propylene) filled with unfunctionalized MWCNTs (Multi Walled Carbon Nano-Tubes), SBR (Styrene Butadiene Rubber) filled with CB (Carbon Black) and PEEK (Poly-Ether-Ether-Ketone) reinforced with CFs (Carbon Fibers).