There are two distinct types of rheometers, which are referred to respectively as rotational and extensional rheometers. Extensional rheometers are used to control the amount of extensional stress or extensional strain that is applied, whereas rotation rheometers are used to control the amount of shear stress or shear strain that is applied. There are four different shearing planes that can be used when determining the rheological properties of a substance, and there are many different types of ...