Influence of rigid segment and carbon nanotube concentration on the cyclic piezoresistive and hysteretic behavior of multiwall carbon nanotube/segmented polyurethane composites

The cyclic piezoresistive behavior of multiwall carbon nanotube/segmented polyurethane (MWCNT/SPU) composites is investigated by varying the amount of rigid segment (RS) content (15, 30 and 50 wt% RS) of the polymer and MWCNT concentration (2, 4 and 6 wt% MWCNT). The mechanical and piezoresistive responses during the first loading-unloading cycle are quite different to those of the subsequent cycles, and become repeatable as the number of cycles increases. The cyclic piezoresistive response of the elastomeric MWCNT/SPU composites showed nonlinear, non-monotonic and hysteretic behavior during loading-unloading to 10% strain, showing positive and negative piezoresistive effects, which depend strongly on the RS content and, to a less extend, on the MWCNT weight content. It is shown that the strain sensing capabilities of this kind of composites under large strains can be tailored based on the RS and MWCNT contents.