Mooney viscosity can basically reflect the degree of polymerization and molecular weight of synthetic rubber. Mooney viscosity reflects the quality of rubber processing performance, molecular weight, and distribution range. The Mooney viscosity value is closely related to plasticity. A high viscosity value mainly affects the processing performance of raw rubber and synthetic rubber, indicating that rubber has a high molecular weight and poor plasticity, while rubber has a low molecular weight and good plasticity. If the Mooney viscosity is too high, it is not easy to process; If the Mooney viscosity is too low, the tensile strength of the vulcanized product will be low, and the performance may not meet the requirements. The reasonable Mooney viscosity value of Control rubber is beneficial to the processing technology of rubber mixing, calendering, extrusion, injection and molding vulcanization. Vulcanized rubber can obtain good physical and mechanical properties. What is the Mooney viscosity method? The Mooney viscosity method uses a Mooney viscometer to measure the plasticity of rubber materials. The testing principle is to measure the shear resistance generated by the sample to the rotation of the rotor under certain temperature, time, and pressure, and the plasticity of the rubber material is represented by the different torque sizes. The structure of the Mooney viscometer is shown in the figure below.
In order to heat the mold cavity to a constant temperature of (100±1) °C, then put the sample into the mold cavity and preheat for a certain period of time, and the viscometer starts to work. When the rotor rotates, observe the scale value of the instrument. The displayed value is the Mooney viscosity value of the rubber material, abbreviated as Mooney viscosity. The higher the Mooney viscosity, the higher the viscosity of the rubber (i.e., the lower the plasticity of the rubber). The Mooney viscosity value varies depending on the test conditions, so the test recording method should indicate the test conditions. Usually, Mooney viscosity is expressed as ML1 +4100°C. Where, M shows Mooney, L1+4, 100°C represents a large rotor (diameter 38). 1mm) The torque value measured when preheating for 1 minute and rotating for 4 minutes is indicated by a dial indicator. The measurement range of Mooney viscosity is 0 to 200. Mooney viscosity reflects the viscosity of rubber under specific conditions and can be directly used as an indicator to measure the rheological properties of rubber. However, due to the slow speed and small shear rate of this method, it can only reflect the rheological properties of the rubber at low shear rate. If the test speed is increased, the results are closer to the rheological properties in actual processing. The Mooney viscosity method is fast and simple to test the plasticity of rubber materials, without the need to make standard-shaped samples. In addition, the method can also easily measure the scorching time of the rubber material (i.e., the diameter is 30. After the 5mm rotor is preheated at 120°C for 1min, the time required for the Mooney viscosity to decrease to the bottom and then increase by 5 Mooney values is called scorching time. Therefore, the concept of Mooney viscosity has a wide range of applications in scientific research and production.
