Abstract: The present invention provides a method for creating durable blends of polystyrene and polyolefin. The blends of the present invention have improved mechanical properties evidenced by measurement of impact strength, tensile strength, and elongation at break. Polyolefin is first crosslinked by creating a melt of polyolefin and a small amount of peroxide in a mixer at elevated temperature. The crosslinked polyolefin is then melt-blended with polystyrene at elevated temperature. Finally, a styrene-butadiene-styrene block copolymer is mixed into the melt. The method of the present invention can be applied to various blend systems of otherwise incompatible polymers provided it contains at least one component and a compatibilizer that are crosslinkable.