Viscosity refers to the thickness of a material. Industries use a variety of instruments to perform tests on different substances. In the case of rubber or a compound, standard test methods involve knowing such characteristics or properties as:
- Pre-Vulcanization Characteristics
- Stress Relaxation
- Viscosity
A Mooney viscosity test involves measuring these diverse aspects, particularly viscosity. The tool to achieve the right measurements is the Mooney viscometer.
What Is a Mooney Viscometer?
A Mooney viscometer is as the name clearly indicates, an instrument meant for usually measuring the viscosity of rubber. It bears the name of its inventor, American physicist Melvin Mooney (1893–1968), who worked for the American Rubber Company. This type of viscometer contains a rotating spindle or disc and heated dies. As the substance flows through the die cavity, it surrounds and overflows the spindle. Using the torque of the spindle, the technician calculates the Mooney viscosity. Due to the constraints imposed on temperature and pressure, the instrument can successfully measure the effects both time and temperature will have on the viscosity of the substance in play.
Why Is Measuring Viscosity of Rubber Important?
In the rubber industry, before the final form of vulcanization, rubber or a compound material will have to undergo various process methods. If the viscosity of the rubber varies from the original, it can result in problems during such processes as
- Calendaring – used to coat, smooth, or thin
- Extrusion
- Injection molding
By using the Mooney viscosity test, the technicians can make certain the viscosity parameters remain within certain limits
However, this is not the only reason why industries employ the Mooney viscometer.
Applications of the Mooney Viscosity Test
Advances in technology have produced a vast array of new polymers and rubber compounds. A company planning to employ them in creating components or as a product needs to be certain they do not make a wrong choice. Industry experts need to select the right product at the right dosage and combine it with the right process at the right temperature. This requires knowing how the material will react under temperature variations.
Using the Mooney viscometer allows the technicians to:
- Predict the Behavior of Rubber: This specifically refers to how the material will behave in terms of temperature and processing time.
- Control Quality
- Grade Rubber
- Minimize wastage
At the same time, by using the Mooney viscosity test correctly, a company can save in certain areas, therefore making the implementation of the process a fiscally responsible and cost-effective measure.