Linear Non‐conjugated Dienes From Biomass As Termonomers In EPDM Synthesis, 3. Conventional Versus Metallocene Catalysis

The synthesis in the presence of the rac-EtInd 2 ZrCl 2 /MAO catalytic system of new EPDM terpolymers based on linear non-conjugated dienes issued from biomass, 3,7-dimethylocta-1,6-diene (3,7-DMO) and 5,7-dimethylocta-1,6-diene (5,7-DMO), is described. 5,7-DMO can be readily incorporated in ethylene/propylene (E/P) chains, while 3,7-DMO does not react in the presence of the metallocene catalyst. The reactivity of these linear dienes is compared with that of 2-ethylidenebicyclo[2.2.1]hept-5-ene (ENB), the preferred termonomer for the industrial synthesis of EPDMs. With the metallocene catalyst, the reactivity of 5,7-DMO is close to that of ENB, suggesting that 5,7-DMO is a good candidate for the synthesis of a new EPDM. A comparison with the conventional catalysis based on vanadium systems shows that the advantages of the metallocene catalysis consist in higher catalyst activities and higher incorporation rates of the termonomers in the polymer without any noticeable side reaction. The structural and physico-chemical characteristics of the various terpolymers, investigated by NMR, SEC and DSC, also underline that the use of metallocenes allows one to prepare EPDM based on linear dienes, with an homogeneous chemical composition and a controlled structure.