Antistatic High‐Density Polyethylene ( <scp>HDPE</scp> )/Conductive Carbon Black ( <scp>CCB</scp> ) Composites for Automotive Parts: Influence of <scp>CCB</scp> Structure and Molding Technique

ABSTRACT The development of polymer composites with controlled electrostatic dissipation is crucial for safety‐critical applications, such as automotive fuel‐handling systems, where static charge accumulation may lead to ignition hazards. This work examines the combined effects of matrix rheology, filler structure, and molding technique on the electrical and mechanical behavior of HDPE/conductive carbon black (CCB) composites. Two HDPE grades with different melt flow indices and two CCBs with distinct surface areas were compounded by twin‐screw extrusion and shaped by compression (CM) and injection molding (IM). TGA and DSC confirmed the expected filler contents (~10 wt%) and indicated reduced crystallinity in the composites. The addition of CCB improved stiffness (30%–80%) and tensile strength (10%–17%) depending on both HDPE and CCB type, while rheological data showed that highly structured CCBs promote strong percolated networks. Surface resistivity measurements revealed that electrical percolation depends not only on the CCB structure but also on the molding technique. IM specimens exhibited higher resistivity due to flow‐induced orientation and the formation of a resistive skin layer; removal of this layer significantly decreased resistivity. These results demonstrate that achieving reliable antistatic performance in HDPE/CCB composites requires simultaneous optimization of filler morphology and processing route to tailor conductive pathways.