Rheological Properties and Extrusion Characteristics of Polycarbonate/Carbon Black Composites

The rheological properties and extrusion characteristics of electrically conductive polycarbonate (PC)/carbon black (CB) composites are investigated. Our results reveal that both the zero shear viscosity and shear thinning are increased as the content of carbon black increases. It is observed that the viscosity of the PC/CB composite in the processing region is slightly lower than that of the polycarbonate matrix when the carbon content is below 10 wt%. It is also found that the melt tension and extensional viscosity of the PC/CB composites steadily increases with increasing the carbon black content. On the other hand, the cut-off speed at which the melt fiber was cut in the fiber spinning experiment decreases drastically as the CB concentration increases. The extrusion process of the composites is numerically simulated using the modified Lee-Han melting model and the results are compared with the experimental results. It should be noted that the decrease in the viscosity in the processing region reduces pressure buildup during extrusion. The effects of carbon black on electrical and mechanical properties of the composites are also discussed.