Improvement of polyimide/polysulfone composites filled with conductive carbon black as positive temperature coefficient materials

ABSTRACT In this study, polyimide (PI)/polysulfone (PSF) blends filled with carbon black (CB) were developed for the use as positive temperature coefficient (PTC) materials in order to achieve the volume resistivity as lower than 10 4 Ω.cm at room temperature. The weight ratios of PI/PSF were various from 100/0 to 10/90 with CB varied from 0 to 20 wt%. The use of conductive filler was reduced when PSF was blended with PI; the blends clearly possessed a percolation threshold decreased by 90%. The electrical conductivity of the CB‐filled blends was higher than those of CB‐filled pure PI. The transition temperature for PTC material was reported in the range of 180 to 210 °C. The preferential location of CB filler in PI domains could be observed using the optical microscope. In addition, the composites met the standards for the obtained mechanical and thermal properties, exhibiting the potential use as PTC materials. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137 , 48482.