IMPERFECT SQUEEZING FLOW VISCOSIMETRY WITH A WIDE PLATE AND A SHALLOW CONTAINER

Imperfect squeezing flow is defined as the outward and upward flow of a liquid in a shallow container compressed at a constant displacement rate with a wide plate (liquid depth to plate diameter on the order of 1:10-1:20). The viscosity of Newtonian silicon oils could be determined with an accuracy of about 5 % using such an array, with a plate and containers having a diameter on the order of 10 and 14 an, respectively, and liquid depth on the order of 5-6 mm. The same procedure, however, was not very effective for determining the rheological constants of a commercial mustard and especially ketchup. In the latter case this was probably the result of self-lubrication by a low viscosity liquid film, which distorted the force-time relationship. The effect was even more prominent when samples of the same ketchups were tested in a coaxial viscosimeter. Because of this problem the procedure as described can only be used as a crude empirical method to distinguish between liquid foods having very different rheological properties.