Kinetic Study of Chain Transfer Reactions upon 1-Hexene Polymerization on Highly Active Supported Titanium–Magnesium Catalysts

Resumo

Data on the effect the concentrations of the monomer, triethylaluminium, and hydrogen on the molecular weight of polyhexene upon 1-hexene polymerization over supported titanium–magnesium catalyst are obtained. The ratios between propagation rate constant and the rate constants of the reactions of polymer chain transfer with monomer, triethylaluminium (AlEt₃), triisobutylaluminium, and hydrogen are calculated. The data allow us to estimate the effect of individual reactions of chain transfer on the polymer’s molecular weight under different polymerization conditions. The data help to select polymerization conditions for obtaining polyhexene of a desired molecular weight. The heterogeneity of active centers is observed in the reaction of chain transfer with hydrogen when using AlEt₃ as co-catalyst, which alters the polymer’s polydispersity when the concentration of hydrogen is varied in the reaction mixture. The molecular weight distribution is analyzed via resolution into Flory components for polyhexene characterized by different polydispersity.