Influence of rigid segment content on the piezoresistive behavior of multiwall carbon nanotube/segmented polyurethane composites

Tensile piezoresistive properties of multiwall carbon nanotube (MWCNT)/segmented polyurethane (SPU) composites comprising 15, 30, and 50 wt % rigid segment (RS) contents and 2, 4, and 6 wt % MWCNT contents are investigated. The physicochemical properties of such composites are used to better understand their mechanical and piezoresistive behavior. Infrared spectra shows that for 15 and 30 wt % RS composites the addition of MWCNTs promotes a more structured RS domain which increases the phase separation, while for 50 wt % RS composites the MWCNTs disrupt the RS domains of the polymer with a high phase separation. Overall, MWCNT content has less effect on the phase separation than RS content. The composites with 6 wt % MWCNT content reached electrical conductivities of the order of ∼10−1 S/m using 15 and 50 wt % RS polymers. Upon deformation, composites with 15 wt % RS and 4 wt % MWCNT achieved changes in electrical resistance of the order of 5000 times their unstrained value, which are outstanding values that can be exploited for applications such as human motion detection. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44448.