Effects of blending sequence on properties of ternary polyolefin blends

Abstract

Effects of blending sequence on properties of a ternary polyolefin blend based on isotactic polypropylene (PP) have been studied. The ternary blend was composed of three components: PP, metallocene ethylene–octene copolymer (mPE) and high density polyethylene (HDPE), with PP as matrix, mPE and HDPE as toughened fillers. The ternary blends were prepared by melt mixing in a twin screw extruder under three different blending procedures: simultaneous mixing of the three components, premixing of mPE and HDPE followed by mixing with PP and premixing of PP and HDPE followed by mixing with mPE. It was found that Izod notched impact strength of the ternary blends prepared by simultaneous mixing was dramatically improved, and blends prepared by premixing of mPE and HDPE followed by mixing with PP had a higher modulus and a higher elongation at break than those of other ternary blends. The dependence of the microstructure on blending sequence was investigated.