CHAIN TRANSFER-REACTIONS IN OLEFIN POLYME RIZATION WITH ETHYLENEBIS(TETRAHYDROINDENYL)ZIRCONIUM DICHLORIDE COMBINED WITH METHYLALUMOXANE

Propene polymerization was conducted with ethylenebis(tetrahydroindeny l)zirconium dichloride combined with methylalumoxane at 0, 20, and 40 degrees C. The activity increased linearly with an increase in propene pressure regardless of polymerization temperature. The molecular weig hts of the polymers obtained at 0 degrees C were independent of the pr opene pressure, while those at 20 and 40 degrees C slightly increased with an increase in the propene pressure. The polymers obtained at 40 degrees C contained vinylidene end groups in addition to a small amoun t of an internal olefin group. The amount of the vinylidene groups dec reased with increasing the propene pressure or decreasing polymerizati on temperature. On the other hand, the amount of the internal olefins was independent of the propene pressure. The copolymerization of prope ne with ethylene was also conducted with this catalyst system at 0, 20 , and 40 degrees C. The produced polymers had a vinylidene end group e xclusively. Moreover, the propene unit also existed at the saturated i nitiation end. From these results, it was concluded that the chain tra nsfer reaction with this catalyst system was caused mainly by propene monomer when the propagation proceeded via 1,2-addition.