A continuous-shear rheometer for measuring total stress in rubber-like materials

An instrument is described for measuring both the tangential and normal components of stress in rubber-like materials subjected to uniform rates of shear within the approximate range 0.01-10 sec.-1 It is based on the Weissenberg rheogoniometer, the sample being sheared between a conical rotor and plane stator, and the stress being measured by the distortion of springs. The apparatus is capable of operating at temperatures up to more than 200° C., and the construction is sufficiently robust to permit the sample to be moulded in the test space and to withstand the relatively high stresses developed during shear. Elastic recovery can be measured by movement of the rotor when the drive is disengaged. Test results on a sample of polythene show a normal stress component several times greater than the tangential component.