Is Metallocene Polyethylene Blend with HDPE More Compatible Than with PP?

Abstract

The interfacial tension between metallocene polyethylene (MCPE) and polypropylene (PP) is found to be very low which indicates submicron dispersions of polyolefins are accomplished even with high-melt index of PP. Again, MCPE exhibits sharp relaxation at sub-ambient temperature. High and low molecular weight metallocene catalyzes high-density polyethylene (HDPE) and forms a miscible blend. This chapter examines the thermal, mechanical and viscoelastic behaviors of MCPE blended with conventional polyolefins, for example, HDPE and PP. This chapter presents evidence that both blends are immiscible and the extent of compatibility of the HDPE–MCPE blends is larger than the PP–MCPE blends by both thermal and relaxation studies. It is well known that polyethylene and polypropylene form compatible blends whereas polyolefins and nylon 6 form incompatible ones, although both types of blends are thermodynamically immiscible. Metallocene polyethylene blends with HDPE and PP are immiscible but the degree of compatibility is larger for the former system compared to the latter that reminds the old idea “like dissolves like” is also valid in the polyolefin blends.