VALIDATION OF COGSWELL CONVERGENT FLOW-ANALYSIS

The behavior of two polymers, namely, low-density and linear low-densi ty polyethylenes, was studied in transient and steady-state shear and elongational flows. The predictions of Wagner's model with a damping f unction using a generalized invariant were calculated. The model appea rs to be suitable for predictions of the shear and elongational transi ent flows on the range of strains experimentally tested. The shear flo w curves can also be recovered by the model on a very broad range of s hear rates. The model is then used to assess extensional data obtained with the convergent flow analysis proposed by Cogswell. (C) 1996 John Wiley & Sons, Inc.