Normal Stress Effects in Polymer Solutions. I. Measurements in a Parallel Plate Instrument

Abstract
Results of some geometrical studies of normal stress effects in a parallel plate instrument have been discussed. The parallelism and the concentricity of two plates are necessary conditions for the quantitative measurement. The rotational velocity of a cup should be kept below about 70 rpm for the apparatus with the cup radii about 6∼8 cm. to avoid the influence of the centrifugal force. Accesses of manometer tubes with the diameter about 2 mm. cause no appreciable disturbances. The influence of side gap may also be neglected. With these experimental remarks, the normal stresses are obtained as a function of the rate of shear.

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