Highly stretchable conductive thermoplastic vulcanizate/carbon nanotube nanocomposites with segregated structure, low percolation threshold and improved cyclic electromechanical performance

Abstract

We investigated electrically conductive nanocomposites made of thermoplastic vulcanizates (TPVs) and multiwalled carbon nanotubes (CNTs) that exhibit highly enhanced stretchability, low electrical percolation threshold, and improved electromechanical durability after cyclic loading. The TPV/CNT nanocomposites were fabricated by compounding pre-vulcanized rubber (PVR) fine particles with a maleic anhydride grafted polyethylene (MA-g-PE)/CNT compound. Our microstructural and morphological investigations showed that using PVR particles, rather than their more common virgin elastomer counterparts, locked the carbon nanotubes in the MA-g-PE phase. This guaranteed the formation of a segregated structure. Furthermore, it was confirmed that the chemical bonding forms between the PVR particles and the MA-g-PE matrix produced an excellent interfacial adhesion between the two phases. This engineered structure increased the TPV/CNT nanocomposites’ stretchability by 300%. Meanwhile their electrical percolation threshold was decreased by ∼50%, when compared with their MA-g-PE/CNT counterparts. Interestingly, the cyclic electromechanical properties were also improved, suggesting the nanocomposites’ great potential for flexible and stretchable electromechanical applications. The mechanisms linking the microstructure and their consequent characteristics were also discussed. Such property combinations can be extremely beneficial in flexible electronics, soft robotics, and health monitoring devices.