Estimation of elongational viscosity of polymers from entrance loss data using individual parameter optimization

The elongational viscosity model proposed by Sarkar and Gupta (journal of Reinforced Plastics and Composites 2001, 20, 1473), along with the Carreau model for shear viscosity is used for a finite element simulation of the flow in a capillary rheometer. The entrance pressure loss predicted by the finite element flow simulation is matched with the corresponding experimental data to predict the parameters in the elongational viscosity model. To improve the computational efficiency, various elongational viscosity parameters are optimized individually. Estimated elongational viscosity for a Low Density Polyethylene (Dow 132i) is reported for two different temperatures. (C) 2002 Wiley Periodicals, Inc.