Polymer Melt Rheology at High Shear Rates

Abstract

Abstract The importance of polymer flow properties during processing has required the development of new on line measurement systems, able to work under rates encountered during industrial processes. This paper will describe a rheometer which is able to study the thermorheological behavior of polymers within industrial injection or extrusion machines. Its main feature is to work at high shear rates which are experimented during production processes; it is equipped with dies of different diameters and lengths, allowing shear rates between 102 to 107 s−1. Some results concerning viscosity and first normal stress differences are presented for high density polyethylene (HDPE), polypropylene (PP) and polypropylene/polyarylamide blends (PP/PA). The plot of viscosity and first normal difference against shear rate for these materials are not linear. Two non Newtonian regions and a third one similar to Newtonian behavior were observed in the wide range of shear rates up to 8.106 s−1.