At least one of the metallocenes is unbridged and is represented by the formula (Cp)2 MX2 wherein each Cp is the same or different and is selected from substituted or unsubstituted cyclopentadienyl, indenyl or fluorenyl, M is zirconium, titanium or hafnium and X, which is the same or different, is a hydrocarbyl radical such as aryl, alkyl, alkenyl, alkylaryl, or aryl alkyl radical having from 1-20