Model for the prediction of bulk temperature changes and pressure losses in rubber compounds flowing through conical dies: An engineering approach

Abstract

The bulk temperature is a very important parameter for the processing of rubber compounds. Currently, standard injection molding simulation is taking into account just shear heating, while elongational heating is neglected by most available software tools. A new viscous model for the prediction of temperature changes in rubber compounds flowing through conical dies and runner segments was deduced where elongational heating is considered as well. Shear viscosity was directly measured on a Capillary Rheometer and elongational viscosity was calculated from the inlet-pressure drops using a new approach. To verify the theoretical calculations experiments on a rubber injection molding machine were carried out by means of a specially designed mold. Varying injection speed and the die angle bulk temperature measurements in the purged material were performed. The measured bulk temperature rise showed a dependence on the flow rate and the cone angle with the flow rate being dominant. The results of the temperature measurements showed good correlation with the model results with an average error being <5%. POLYM.ENG. SCI., 55:701-709, 2015.

Influence of elongational flow generating nozzles on material properties of polypropylene nanocomposites

“…The parameters used in the calculation can be found in Table 4. When measuring the PP, no rise of elongational viscosity at high shear rates could be detected in contrast to the compound characterized by Perko [45]. Therefore, the power law Eq.…”

“…This might be the reason for the underestimation of temperature at these flow rates. The calculation method by Perko also performs quite well for prediction of the pressure (average error = 2.1 MPa; 7.5%), whereas temperature prediction is not as adequate (average error = 3.3°C; 41%). This is mainly caused by the deviations at low volumetric flow rates and the low absolute values of the temperatures as well.…”

“…The additional energy input in the conically and hyperbolically shaped nozzles causes temperature rise and pressure drop that can influence the process as well as the material property. The measured as well as the calculated pressure drop of the standard and the conically shaped nozzle can be found in Fig. and the temperature values are illustrated in Fig.…”

“… Temperature increase as a function of volumetric flow rate for the standard (S) and the conically shaped nozzle (C); measured, calculated values using adiabatic equation and using the Perko et al method .…”

A study on material optimization for polypropylene nanocomposites based on layered silicates using elongational flow devices

“…The pressure drop has been calculated with the help of an engineering approach of Perko et. al [8]. The best hyperbolical nozzle hlR comes along with along with an additional measured pressured drop of approximately 200 bars and the best conical nozzle needs 400 bar additional pressure.…”