Transient shear flow properties of fiber-filled polyethylene melts

The growth and relaxation of shear and normal stresses have been investigated for glass and carbon fiber-filled polyethylene melts over a wide range of shear rates and temperatures by means of a cone-and-plate rheogoniometer. Flow parameters and flow curves characterizing the stress overshoot and relaxation phenomena of the fiber-filled systems were determined experimentally. The influence of fiber loading, fiber size and temperature on the transient flow parameters are discussed.Predictions by the Meister and Bogue constitutive equations were compared with the experimental data for the transient shear and normal stresses. These equations predict satisfactorily the non-linear transient shear flow of polymer melts and its fiber-filled systems.