Carbon black-filled PET/HDPE blends: Effect of the CB structure on rheological and electric properties

The theological and electric properties of blends of poly(ethylene terephth alate) (PET) and high-density polyethylene (HDPE) filled with various types of carbon black (CB) were analyzed in detail in this project. Four types o f CB samples with available values of surface area, particle size, porosity , density, and maximum packing fraction were considered. Blends were prepar ed using an internal mixing chamber at two different rotational speeds, pri or to mold compression of the samples. The rheological properties of the bl ends with varying polymer composition and a constant amount of CB were reco rded in terms of torque variation with time for two shear rates (in terms o f rotational speed). Rheological data were related to the resistivity of bl ends. Results show that the CB structure (porosity, surface area, apparent bulk density, and particle size) largely determine the resulting equilibriu m torque and electrical properties. Furthermore, since CB is preferentially located in the HDPE phase, higher conductivity is observed as the PET cont ent decreases, since the relative CB content in this phase increases. (C) 2 001 John Wiley & Sons, Inc.