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Branched polyethylene was synthesized by ethylene homopolymerization in the presence of a novel metallocene complex of η 5 pentamethylcyclopentadienyl tribenzyloxy titanium[Cp *Ti(OBz) 3] activated by four types of modified methylaluminoxanes(mMAO) which contained different amounts of residual trimethylaluminum(TMA). The activity of catalyst and molecular weight, branched degree and branch length of the resultant polymers depend on the oxidation states of active species of titanium and polymerization temperature. The higher content(%) of residual TMA in mMAO could strongly reduce complexes Ti(Ⅳ) to Ti(Ⅲ) and Ti(Ⅱ) and Ti(Ⅳ) active species was suggested to be more effective for ethylene polymerization. The products obtained were confirmed by 13 C NMR and IR spectra charac|terization to be branched polyethylene with isolated long branch and methyl pendant. There is a remar|kable increase in proportion of methyl pendant with the increase of polymerization temperature. [WT5HZ]
Branched polyethylene was synthesized by ethylene homopolymerization in the presence of a novel metallocene complex of η 5 pentamethylcyclopentadienyl tribenzyloxy titanium [Cp * Ti (OBz) 3] activated by four types of modified methylaluminoxanes (mMAO) which contained different amounts of residual trimethylaluminum (TMA) . The activity of catalyst and molecular weight, branched degree and branch length of the resultant polymers depend on the oxidation states of active species of titanium and polymerization temperature. The higher content (%) of residual TMA in mMAO could strongly reduce complexes Ti (IV ) to Ti (Ⅲ) and Ti (Ⅱ) and Ti (Ⅳ) active species was suggested to be more effective for ethylene polymerization. The products were confirmed to be 13 C NMR and IR spectra charac | terization to be branched polyethylene with isolated long branch and methyl pendant. There is a remar | kable increase in proportion of methyl pendant with the increase of polymerization te mperature. [WT5HZ]