The piezoresistive effect in polypropylene-carbon nanofibre composites obtained by shear extrusion
The piezoresistive effect on poly(propylene) (PP)-carbon nanofibre (CNF) composites fabricated by twin-screw extrusion and compression moulding has been investigated. The electrical and mechanical properties of PP/CNF composites have been obtained as a function of CNF concentration. Electrical conductivity exhibited low thresholds and values close to the required levels for EMI shielding applications at 2.4vol%. Meanwhile the elastic modulus showed an enhancement with a maximum up to 130% for one of the composites at 0.9vol% loading. Further, the piezoresistive response has been evaluated in four-point bending. Positive gauge factors between 2 and 2.5 have been obtained. The highest gauge factors are found within the percolation threshold. The characteristics of the materials and the production technique make them suitable for large scale applications.