IN-SITU POLYOLEFIN ALLOYS

Through sequential copolymerization of appropriate ethylene-propene mixtures into a preformed polypropene, or slightly modified polypropene matrix (PP), it was possible to achieve and optimize some important property balances of the resulting multiphase copolymers, by finely tuning both the nature of the various phases and their volume and viscosity ratios. Thus, optimum stiffness/impact strength was achieved acting on the stereoregularity and molar mass distribution (MMD) of the polypropene matrix; transparency/impact strength by adjusting heterophase to matrix viscosity or density ratios and, finally, softness/transparency by generating large concentrations of highly amorphous ethylene-propene bipolymers (EPM).