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Using a new instrument, the influence of the shear amplitude s0 on the dynamic behavior of polymer solutions up to 700% shear was investigated. At amplitudes <∼100% shear, the dynamic viscosity η1 remained constant, as required by linear viscoelasticity; however, the shear storage modulus G′ decreased considerably. The steady-state flow curve forms the envelope of curves measured with different amplitudes and frequencies, predominantly in the range of higher rates of shear. The more complete analysis of the results is forthcoming.

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Simultaneous measurements of flow birefringence, shear and normal stresses on a 15% solution of polyisobutylene in decalin were performed. They proved that the extinction angle measured in birefringence is identical to the orientation of the principal tensile stress calculated from the normal stress measurements and that the birefringence was proportional to the difference in principal stresses in flow. A detailed discussion of the significance of this result is given with a possibility of a far-reaching generalization of the mechanical behavior of high polymer solutions.

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