Measurement of the coefficient of dynamic friction at extrusion processingconditions

The dynamic friction coefficients of several polymers have been investigate d using a specific rotating device similar to an extruder. The increase in temperature during the measurements made it necessary to develop a theoreti cal approach in order to interpret the experimental data correctly. The rot ation speed and particle shapes were found to have little influence on the friction coefficient. For HDPE and PVC, the friction coefficient decreased slightly with interfacial temperature, whereas it remained constant for PP. The order of magnitude of the friction coefficients was similar to what ha s already been published in the literature.