Evaluation of rheological behaviour of some thermoplastic polyurethane solutions

In this paper some rheological properties of two type of thermoplastic polyurethane elastomer solutions are presented. For preparation of these solutions we utilized dimethylformamide as solvent. The concentration values and temperature of the polyurethane solutions was ranged between 7% and 15%, and respectively 30–60°C. Rheological measurements were effectuated with a rotating viscosimeter (Rheotest-2, Germany). Processing of experimental results give off the material constant value (k) and the extremities viscosity (η0 and η∞). These values were verified with some rheological models. Interpretation of rheological properties by Cross model proof that the solutions belong to the pseudoplastic category (viscosity decreasing with increasing shearing rate).