Low magnetic field-induced morphological regulation in isotactic polypropylene/poly(ε-caprolactone)/carbon black composites for high electrical conductivity and conductive anisotropy

Morphological regulation and selective distribution of conductive fillers in conductive polymer composites (CPCs) has been well demonstrated to efficiently improve electrical conductivity and conductive anisotropy. Herein, the conductive network was fabricated in isotactic polypropylene/poly(ε-caprolactone)/carbon black (iPP/PCL/CB) composites via the selective distribution of CB particles in PCL and the morphological regulation of the composites to form continuous PCL/CB phase. The magnetic particles (Fe3O4) and CB particles were fist selective dispersion in PCL phase. The continuous PCL/CB phase was then formed from droplets by the arrangement of Fe3O4 in a low magnetic field (~25 mT). As a result, the electrical conductivity and conductive anisotropy was improved by the formation of CB conductive network. The electrical conductivity of the composites with 5.4 wt% CB increased from 7.14 × 10-9 to 0.0014 S/m, and the percolation threshold of the composites deceased from 4.10 to 0.70 wt% after the magnetic treatment. Furthermore, the composites after the magnetic treatment exhibited the conductive anisotropy and the high conductivity along the treatment direction, the anisotropic index of ~102 was found in the composites with 5.4 wt% CB particles.