Direct measurement of steady state shear viscosity
by Michele Scacchi and Denis Venturoli, Evercompounds S.p.A., and Mauro Belloni, Gibitre Instruments S.r.l.
The Mooney viscometer (MV) was invented by Dr. Melvin Mooney (ref. 1) in the 1930s, and it was the first rotational rheometer available in the rubber industry. Mooney viscosity is measured by a metal disk embedded in a rubber specimen contained in a cylindrical testing die cavity maintained at a specified pressure and temperature. The flat grooved disk is slowly and continuously rotated in one direction for a specified time; there is a rotational shear flow between opposing flat surfaces. The resistance to this rotation offered by the rubber is measured in arbitrary torque units (MU) as the Mooney viscosity of the specimen.