Preparation and Characterization of Isotactic Polypropylene/ High-Density Polyethylene/Carbon Black Conductive Films with Strain-Sensing Behavior

摘要

Novel conductive films with a unique strain (e)-sensing behavior and based on a blend of isotactic polypropylene (iPP), high-density polyethylene (HDPE), and carbon black (CB) were fabricated by an extrusion casting method. The morphology and e-sensing behavior of the films were investigated. Scanning electron microscope images showed that the oriented lamellae with a growing direction perpendicular to the extrusion direction were obtained in the HDPE phase and were accompanied by a cocontinuous structure of the iPP phase and HDPE/CB phase. The conductive percolation threshold (m_c) and resistivity–e behavior of the thin films are affected by the drawing ratio during the process of film preparation. The m_c and electrical resistance of the iPP/HDPE/CB composite films increased with the drawing ratio. The gauge factor of the films within the elastic region decreased with increasing drawing ratio. Furthermore, the result of iPP/(HDPE/CB) 40/60 with a high drawing ratio shows that a reversible conductivity was obtained during the cyclic tensile testing (ε=10), but an irreversible conductivity makes the film fail during use at the applied e values of up to 15. This makes them good piezoresistive candidates for e-sensing materials. Moreover, a simple structural model was proposed to describe the reversible and irreversible phenomena in the electrical resistance behavior of the iPP/HDPE/CB films under tensile loading.