Determination of polymer melts flow-activation energy a function of wide range shear rate

Abstract

The majority of the processing of thermoplastic polymers is in melt condition. For example, extrusion, or injection moulding, which are the two biggest plastic processing technologies. Nowadays, there is a need to simulate these processes. The simulations are helpful for the plastic product and mold designers. In these simulations one of the most important internal parameters is the shear viscosity, which depends on the temperature, pressure, molecular weight or structure. So easy to see how important is the top priority precise knowledge of the shear viscosity of plastic melts. The importance of polymer melt flow properties during processing has required continuous research of polymer melt rheology. In a previous article, we described how to measure shear viscosity of polycarbonate from 100 to 105 shear-rate regions with standard and non-standard equipments. In this paper a method is shown to calculate the activation energy of flow of high density polyethylene (HDPE), polystyrene (PS) and polycarbonate (PC). It was shown that shear viscosity and activation energy of flow of the polymers depend on the chemical structure. It was found that more rigid molecular structure results higher values.