Effects of Very Low Strain Measurements with the Extended Dynamic Range (EDR) of the RPA on the Accuracy of Shear Thinning Measurements for Rubber Compounds

The shear thinning or pseudoplasticity characteristics imparted to a rubber compound by different elastomers and reinforcing fillers are very relevant to compound performance in extrusion, calendering, molding, and other factory operations.

In this study, an EDR RPA was used to measure the accuracy of rheological behavior at moderate, low and very low strains, using the Cox-Merz rule to relate to capillary rheometry.  Model rubber compounds were prepared and tested.  Processability characteristics were measured for these mixed stocks using the capillary rheometer as well as the EDR RPA.  Comparisons were made of the performance behavior for these compounds.