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Estimation of Entry Pressure Drop during Conical Die Flow of Carbon Black-Filled Rubber Compound

The flow behavior of polymer melts in a conical die extrusion was discussed in the present paper. On the basis of simplified suppositions, a mathematical model for estimation of entry pressure drop was established by using a tensor analysis method. The rheological properties of rubber compound, such as flow curves, viscosity, entry pressure drop, and extrudate swell, were measured by employing a capillary rheometer in a temperature range of 90–130° C and apparent shear rates varied from 50 to 103 s-1. It was found that the shear flow for the sample obeyed the Power law, and the first normal stress difference increased with increasing shear rates at the channel wall as an exponential function. Furthermore, the entry pressure drop during extrusion of the samples was estimated by using this model. The results showed that the predictions of entry pressure drop were basically consistent with the measured data from the experiments of the sample.