Effect of Nano-Particle Filler Type on the Piezoresistance of Polyethylene Composites

This study examines the piezoresistive behavior of polyethylene (PE) composites containing different types of nano-particle fillers. The fillers investigated are single-wall carbon nanotube (SWNT), multi-wall carbon nanotube (MWNT) and graphene nanoplatelets (GNP), which were dispersed in PE through melt blending in concentrations ranging between 0.5–10 wt%. The lowest percolation threshold and highest electrical conductivity was found for SWNT composites, followed by MWNT and GNP. The piezoresistance of the nano-particle-PE composites was investigated and a negative piezoresistance behavior was observed signifying a reducing mean inter-particulate distance in the composites. The highest sensitivity was exhibited by MWNT and SWNT composites at compositions closer to the percolation threshold. The time dependence of piezoresistivity was also investigated through stress relaxation and cyclic loading experiments.