Investigation of the predictive capability of advanced differential constitutive equations for polymer melts under different flow conditions

Abstract

The predictive capabilities of three models (modified White-Metzner model, eXtended Pom-Pom model and newly proposed modification of the Leonov model) are tested for steady shear and uniaxial extensional flows of LDPE, mLLDPE and PVB melts. The input low-shear-rate viscosity data was measured on ARES Rheometrics parallel plate rheometer, whereas RH7-2 capillary rheometer was used for the determination of shear viscosity (capillary), first normal stress coefficient (slit die) and uniaxial elongational viscosity (Cogswell method). A newly proposed 'effective entry length correction' has been applied to deal with all extensional viscosity data.