Synthesis, characterization, rheological and thermal behavior of metallocene ethylene-norbornene copolymers with low norbornene content using pentafluorophenol modified methylaluminoxane

Ethylene-norbornene copolymers were synthesized using rac-ethylene bis(indenyl) zirconium dichloride/pentafluorophenol modified methylaluminoxane. First, the effect of using a modifier in combination with a low ratio of Al/Zr on the catalyst activity and co-monomer incorporation was studied. The results of copolymerization reveal a 20% co-monomer incorporation improvement and a rise of activity by 2-fold in the presence of the modifier. Rheological measurements show a higher molecular weight in copolymers synthesized using modified methylaluminoxane. The alternative and dyad block microstructures of copolymers become possible in the case of a norbornene content of more than 14mol%. Second, the effect of co-monomer content on the rheological and thermal behavior of the synthesized copolymers was investigated. The results of the rheological study indicate a lower molecular weight in samples containing a higher norbornene content. Dynamic mechanical thermal analysis confirms the influence of different microstructures on the glass transition temperature. The crystal structure of copolymers having a higher molecular weight is emphasized using wide angle X-ray scattering and DSC even with a greater incorporation of norbornene. (c) 2015 Society of Chemical Industry