Effect of molecular weight and long chain branching of metallocene elastomers on the properties of high density polyethylene blends

In this work, rheological properties and morphological characteristics of blends based on high density polyethylene (HDPE) and two different grades of poly(ethylene-co-octene) metallocene elastomers (EOC) were studied. These elastomers were commercial samples differing in molecular weight, and rheology index (DRI). Blends were processed in a single screw extruder (L/D = 32), at 230 degreesC and 50 rpm, using mass fraction weight percent of EOC in the range from 5-80%. The rheological properties were evaluated in dynamic experiments at 190 degreesC and frequency range from 10(-1) s(-1)-10(-2) s(-1). The blends exhibited pseudoplasticity and complex rheological behavior. That complex behavior was intensified by increasing molecular weight and long chain branching proportion (DRI) of EOC elastomers. The morphological characterization was carried out by using scanning electron microscopy (SEM). The blends exhibited dispersed morphologies with EOC domains distributed homogeneously and with particle size inferior to 2 pro. (C) 2003 Elsevier Ltd. All rights reserved.