Conductive mechanism of carbon black/polyimide composite films

Abstract

During the fabrication of black polyimide composite films, it is common to introduce carbon black (CB) into this composite system. The introduction of CB significantly decreases the resistivity of the films and consequently has a great effect on the inherent insulation property of polyimide. Here, the exploration of the conductive mechanism of CB/polyimide composite films is aimed to explain the change on resistivity fundamentally. In this study, two kinds of representative CBs were chosen to prepare CB/polyimide composite films. The rudiment of the conductive mechanism was built up based on the resistivity curves, and scanning electron microscopy (SEM), tensile, thermal gravimetric analysis, Fourier transform infrared (FT-IR) spectroscopy, UV, Raman and X-ray diffraction (XRD) were conducted to confirm it. The experimental results further verified the mechanism and gave us a chance to propose an integrated conductive mechanism including three sections (tunneling effect mechanism, conductive network mechanism and doping mechanism) for CB/polyimide composite films. As the conductive mechanism has been understood, it paves the way for optimization of the fabrication of conductive black polyimide films and insulating black polyimide films, even other colorful polyimide composite films.