IN-SITU POLYOLEFIN ALLOYS

Through sequential copolymerization of appropriate ethylene-propene mi xtures into a preformed polypropene, or slightly modified polypropene matrix (PP), it was possible to achieve and optimize some important pr operty balances of the resulting multiphase copolymers, by finely tuni ng both the nature of the various phases and their volume and viscosit y ratios. Thus, optimum stiffness/impact strength was achieved acting on the stereoregularity and molar mass distribution (MMD) of the polyp ropene matrix; transparency/impact strength by adjusting heterophase t o matrix viscosity or density ratios and, finally, softness/transparen cy by generating large concentrations of highly amorphous ethylene-pro pene bipolymers (EPM).