Electrical resistivity of polycarbonate/multiwalled carbon nanotube composites under varying injection molding conditions

Abstract Multiwalled carbon nanotube (MWCNT)‐filled polycarbonate composites were prepared by a corotating intermeshing twin‐screw extruder. The surface resistivities of compression‐ and injection‐molded specimens were quite different, the difference ranging from 10 3 to 10 7 Ω/sq at varying MWCNT concentrations. The surface resistivity of the injection‐molded specimen at 2 wt % loading varied up to 10 5 Ω/sq in the specimen thickness direction and up 10 4 Ω/sq in the polymer flow direction with respect to the gate. The difference in surface resistivity with the positions of injection‐molded specimen was confirmed with the morphology, which showed the difference in MWCNT number density (numbers/surface area). There was no significant effect on surface resistivity with injection pressure, holding pressure, and molding temperature. The specimens prepared at the injection speed of 13 mm/s showed surface resistivities 10 3 –10 4 Ω/sq depending on the positions, which was comparable with the compression‐molded specimens, which had a surface resistivity of 10 3 Ω/sq. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009