Synergistic effects of carbon black and carbon nanotubes on the electrical resistivity of poly(butylene‐terephthalate) nanocomposites

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In this study, novel electrically conductive polymeric nanocomposites based on polybutylene terephthalate ( PBT ) filled with commercial carbon black ( CB ) and carbon nanotubes ( CNT s) at different relative ratios have been investigated. Field emission scanning electron microscope ( FESEM ) analysis revealed how a good nanofiller dispersion was obtained both by introducing CB and CNT . Melt flow index measurements highlighted that the processability of the nanocomposites was heavily compromised at elevated filler amounts, and the viscosity percolation threshold was established at 3 wt% for CNT s and between 6 and 10 wt% for CB nanocomposites. Differential scanning calorimetry ( DSC ) measurements evidenced how the presence of CNT slightly increased the glass transition temperature of the materials, and an increase of 12°C of the crystallization temperature was obtained with a CNT amount of 6 wt%. Also the crystalline fraction was increased upon CNT addition. Electrical resistivity measurements evidenced that the most interesting results were obtained for nanocomposites with a total filler content of 6 wt% and a CNT / CB relative amount equal to 2:1. The synergistic effect obtained with the combination of both nanofillers allowed the achievement of a rapid surface heating through Joule effect even at applied voltages of 2 V.