An improvement in a rheometer and the method for measuring rheological properties of a viscoelastic test specimen at different temperatures, at which different temperatures the viscoelastic properties exhibit a relatively wide difference, wherein the test specimen is placed between and is coupled with opposed plates, one of the opposed plates is oscillated angularly relative the other of the opposed plates, and the angular displacement of one of the plates relative to the other of the plates and the torque associated with the relative angular displacement are measured within a predetermined optimum range of torque and angular displacement for determining the rheological properties, couples a first contact surface on one of the opposed plates with the test specimen to establish a first contact area between the one of the opposed plates and the test specimen when the test specimen is at one of the different temperatures, and couples a second contact surface on the one of the opposed plates with the test specimen to establish a second contact area between the one of the opposed plates and the test specimen when the test specimen is at another of the different temperatures, the first contact area being different in area from the second contact area such that, by virtue of the difference in area between the first and second contact areas, the torque and the relative angular displacement measured at each of the one and the another of the different temperatures fall within the predetermined optimum range.
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