Numerical description of shear viscosity functions of long-chain branched metallocene-catalyzed polyethylenes

The viscosity functions of polymer melts are of high interest, as they are the base for the modeling of shear dominated processing operations. The description of shear viscosity functions with formulas based on physical parameters has been an important objective in rheology. The well-known Carreau-Yasuda-model is successful in the case of linear polymers, but not generally for long-chain branched materials. In order to describe the viscosity functions of distinct types of metallocene-catalyzed polyethylenes with long-chain branches (LCB-mPE), an extended Carreau-Yasuda-model is introduced. Additionally, it is shown that the phase angle usually measured by dynamic-mechanical experiments can be calculated with high accuracy from the complex viscosity as a function of the angular frequency.