Relationship between melt shear viscosity and molecular parameters based on high impact polystyrenes in capillary extrusion

The flow behaviour of three high impact polystyrene (HIPS) melts in extrusi on has been investigated by using a capillary rheometry in a wide range of shear rates. It was found that the relationship between end pressure drop a nd apparent shear rate approximately obeyed the index law; the shear flow b ehaviour of the sample melts was more in keeping with the index law at high er shear rates than at lower shear rates; and the dependence of the apparen t sheer viscosity on temperature could be described by the Arrhenius equati on under the experimental conditions. On the basis of comparison of the she ar-sensitivity and the temperature-sensitivity for the melts, the relations hip between steady-shear melt viscosity and molecular parameters was discus sed. (C) 1999 Elsevier Science Ltd. All rights reserved.