Copolymerisation properties of siloxy-substituted bis(indenyl)zirconocene catalysts: Modified rheological behaviour

The combination of the copolymerisation ability and vinyl end group selecti vity of siloxy substitution of ethylene-bridged bis(indenyl) zirconium dich lorides suggest these catalyst as potential ones for the production of poly ethylene containing small amounts of long chain branching. The role of the polymerisation conditions with these highly active catalysts can clearly be seen. Furthermore low contents of multiple branches may occur, even though the probability of attaching several macromonomers into one chain is low. The effect on melt rheological behaviour depends on both the amount of long chain branching and the length of the branch. Moreover the position of the siloxy group is very important. Polymers synthesized with catalysts, where the siloxy group is in position 1, give peculiar rheological behaviour res embling cross-linked networks although the polymers are completely soluble.