Viscosity of copolymers containing carbon black

The flow behavior of random copolymers of styrene and butyl methacrylate containing specific carbon blacks varying in surface area were studied at various temperatures and shear rates. Master curves of reduced viscosity as a function of shear rate were prepared for the pure copolymers at 150°C. The superposition required vertical and horizontal shifts, proportional to (a_T)^?1 and (a_T)^.53, respectively, where a_T is the shift factor. With the incorporation of carbon black, the viscous response is non-Newtonian exhibiting a yield stress at increasing filler concentration and surface area. Master curves of viscosity against shear rate were generated at fixed filler loadings and surface areas by using a single horizontal shift factor.