Mooney Viscometer

Mooney Viscometer is a shearing disk viscometer, designed for accurate measurement of viscosity, scorch time and cure rates of the elastomers.

The instrument consists of flat, cylindrical disk, driven by a motor to rotate slowly and continuously in one direction. This disk is embedded into elastomer specimen which is confined in a heated die cavity maintained at specified temperature and kept closed by a specified force. As the disk rotates its experiences a shear strain. This resistance to rotates offered by the elastomer is shearing viscosity which is proportional to mean absolute viscosity of the specimen.

Normally a preheat period is given to the elastomer following which the disk starts to rotate. A initial high viscosity is recorded and then as the viscosity also decreases, to a minimum value Viscosity obtained with large rotor are approximately twice those of small rotor.

The viscosity is reported as under

• Method of sample preparation
• Mooney viscosity number
• Rotor size
• Preheat time
• Time interval to viscosity reading
• Temperature of test

Typical test results are started as under

= 50ML(I+4) 100C

Where

• 50M = Viscosity in mooney units.
• L = Large rotor (for small replace it with 'S')
• I = Preheat time in minutes
• 4 = Time in minute after starting the motor at which the reading is taken
• 100 C = Test temperature