(510c) The Effect of Screw Configuration and Material Composition on Mechanical Properties and Dynamic Rheological Properties of Polypropylene/high Density Polyethylene Blends

In this study, the mechanical properties and dynamic rheological properties of polypropylene/high density polyethylene (PP/HDPE) blends were experimentally investigated by changing the material composition and arranging the screw configuration in the single screw extruder. For a given screw configuration, it was found that material composition had distinct influence on the tensile strength and impact strength of the polymer blends, the tensile strength decreased markedly as the HDPE concentration increased. The Young's modulus increased at the beginning and then decreased with the addition of the HDPE concentration. It was also found that the screw configuration had clear effect on mechanical properties. The tensile strength of polymer blends prepared by screw configuration containing shear elements was higher than that without shear elements. This result may be due to the fact that more uniform two phase microstructure can be attained under shear flow field. But the impact strength was just inversed compared to the tensile strength; this may be attributed to the structure breakage under high shear condition. In addition, dynamic rheological experiment was conducted and the results demonstrated that composition had clear influence on dynamic rheological properties. The storage modulus, loss modulus and complex viscosity decreased along the extruder for a given composition.

Keywords polypropylene/high-density polyethylene blends; single screw extruder; screw structure; mechanical properties; dynamic rheological behavior