Choosing the right Mooney Viscosity

With increasing Mooney or molecular weight, the typical properties of a rubber, such as resilience, compression set and tensile strength, are improved.

On the other hand, molecular weight has a tremendous influence on the flowability of the uncured compound. Since the flowability decreases with increasing molecular weight, the following rule of thumb applies:

• Low viscosity EPDM grades for compounds with low plasticizer content
• High viscosity grades for compounds with high plasticizer content

In continuous curing processes, a high molecular weight grade is preferred to ensure good collapse resistance and shape retention in the uncured state, but a compromise has to be found in terms of extrudability.

 

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