STRUCTURAL NETWORK THEORY FOR A FILLED POLYMER MELT IN LARGE-AMPLITUDE OSCILLATORY SHEAR

The large amplitude oscillatory shear (LAGS) behavior of a high densit y polyethylene (HDPE) pipe resin containing 2% carbon black has been m easured with a sliding plate rheometer incorporating a shear stress tr ansducer. We have evaluated a structural network theory recently propo sed by De Kee and Chan Man Fong for suspensions, in LAGS. This model p rovides for the creation of junctions due to an imposed flow field, an d has been proposed as a generalization of the Lire kinetic rate equat ion, to model the complex behavior of suspensions. A new model, also b ased on the transient network concept, is proposed for filled polymer melts, and has the desirable feature of separating the effects of the filler material from the entanglement kinetics of the pure polymer. Bo th models are able to fis the steady shear viscosity data measured for this material. We find that both models are capable of predicting the LAGS behavior of this material, except for severe conditions.