A Mooney viscometer is an instrument used for measuring the Mooney viscosity of rubbers. It contains a rotating spindle and heated dies, the substance encloses and overflows the spindle and the mooney viscosity is calculated from the torque on the spindle. 

Background

• The working principle of the Mooney viscometer consists in the measurement of the torque necessary to rotate a disc in a cylindrical chamber filled with the rubber compound to be vulcanized. A number proportional with the value of this torque is taken as viscosity index (Mooney viscosity) and is reported in arbitrary Mooney units.

• The rubber compound is introduced under pressure into the test chamber, made up of two halves. Inside the test chamber a disc is rotated by means of a motor. To avoid rubber slippage during the determination, both the chamber walls and the rotor surface are striated.

• The conversion of the torque into viscosity units is made by means of a calibrated flat spring anchored to the rotating disc shaft. The deformations of the shaft are transmitted to the indicating scale. The elasticity of the spring is chosen so that to a torque of 84 daN.cm correspond 100 viscosity units. The chamber is electrically heated and the temperature is kept constant within 0.5 degree C.