A concentric-cylinder rheometer for polymer melts

Abstract

Polymer melt testing devices now commercially available are adequate for studies of the viscometric functions up to moderately high shear rates and the complex viscosity over a wide range of frequencies. However, these devices have characteristics which limit their effectiveness at large shear rates or amplitudes of oscillation. For example in the cone-plate system, material is thrown out of the gap at large rates of rotation or large amplitudes of oscillation. In the case of the capillary viscometer, pressure and temperature are highly nonuniform at large shear rates. This paper describes a rheometer design for measurement of the shear viscosity of melts at high shear rates and also the response to large amplitude oscillatory shear. But only applications to the study of oscillatory shear will be discussed in detail.