Ethylene-butadiene copolymers, 2. Long branching,double bond distribution and their effect on polymer properties

The principal structural characteristics of ethylene-butadiene copolymers prepared with a modified vanadium catalyst are described. The distribution of the butadiene monomeric units, though non-random, is sufficiently homogeneous at low monomeric units content of butadiene (1–3 mole-%) that a ready and efficient vulcanization with sulfur based systems is easily achieved. Long chain branching, which has a detrimental effect on the copolymer properties, can be measured rheologically and controlled at a very low level by the catalyst system. Vulcanized ethylene-butadiene copolymers show improved mechanical properties with respect to high density polyethylene and good processability before curing.