Melt Strength Behavior of Polyethylene Blends

Melt strength data are presented on different types of binary polyethylene blends as linear low density polyethylene/low density polyethylene (LLDPE/LDPE), linear low density polyethylene/high density polyethylene (LLDPE/HDPE) and LDPE/LDPE. Melt strength was assessed from uniaxial tensile experiments with a Rheotens apparatus. In addition, the blends were characterised in terms of a few other rheological properties such as the zero-shear viscosity and the extrudate swell in capillary extrusion. For the LLDPE/LDPE blend pairs synergistic effects were observed for the melt strength and some other properties. No melt strength synergism was observed for the LLDPE/HDPE and the LDPE/LDPE blends. The results are discussed in terms of the Bersted model on the effects of long chain branching on the low-shear melt viscosity of polyethylenes