Processing‐dependent high impact polystyrene/styrene‐butadiene‐styrene tri‐block copolymer/carbon black antistatic composites

The electrical resistivity and morphology of high impact polystyrene (HIPS)/styrene‐butadiene‐styrene triblock copolymer (SBS)/carbon black (CB) blends were studied. Their antistatic sheets were prepared by both compression‐molding and extrusion calendaring process, with their surface morphology observed using scanning electron microscopy (SEM). The SEM images reveal better dispersion of CB achieved in extrusion‐calendering, resulting in low percolation threshold values in HIPS composites. Higher compression ratio and higher drawing speed (corresponding lower sheet thickness) are beneficial to get better CB dispersion, leading to decreased conductivity for the antistatic sheets. SEM images indicate that strong shear forces in extrusion tend to break the conductive network of CB, resulting in increased surface resistivity.