SIMULATION OF THE RHEOLOGICAL BEHAVIOR OF POLYMER BLENDS BY FINITE-ELEMENT ANALYSIS

A least-square finite element model was used to model the rheological behavior of both homogeneous and two-phase polymer blends, and their v iscosity was calculate over a range of shear rates. The analysis was c arried out for a pressure flow situation through a wide rectangular ch annel. Homogeneous blends were simulated by a model consisting of a la rge number of alternating layers of A and B components parallel to the flow direction using the adhering layers concept. Heterogeneous blend s were simulated by similar alternating layers separated by very thin interlayers. In modeling the negative deviation behavior, associated w ith the flow characteristics of immiscible blends, the interlayers wer e assumed to have a viscosity more than one order of magnitude lower t han either component. Viscosity values for the interlayers higher than both polymers were used, on the other hand, to represent positive dev iation behavior, which is synonymous with the flow behavior of compati bilized blends. To test the accuracy of the model, the computed viscos ity results were compared with the values calculated by the more widel y quoted equations and also with published experimental data. (C) 1997 John Wiley & Sons, Inc.