Melt rheology of LDPE and glass bead filled LDPE composite

The effects of shear rates and temperatures on the melt shear viscosity (et a(w)) and the relationship between the first normal stress difference (N-1) and the wall shear stress (tau(w)) of low density polyethylene (LDPE) and glass bead filled LDPE composite, over a temperature range from 130 to 170 degrees C and shear rates varied from 10(0) to 10(3) s(-1),have been invest igated by employing a capillary rheometer. With a rise of temperatures and increasing shear rates the melt viscosity decreases nonlinearly. The melt f low obeys the power law and the power law index increases with a rise of te mperature. N-1 is approximately an exponential function oft,. The dependenc e of eta(w) on temperatures basically accords with the Arrhenius expression . Under the same test conditions, the eta(w) and N-1 of the composite melt are somewhat lower than those of the pure LDPE melt. On the basis of the pr edecessors' work, an equation describing the relationship between N-1 and p ressure drop has been presented in this article. Good agreement is shown be tween the predicted N-1 values and the measured data from the melts.