Synthesis of linear polyethylene on supported ziegler-natta catalysts. Review

Abstract

The main lines of development of the technology of the synthesis of linear polyethylene are reviewed and work concerned with the aspects of its synthesis analysed. The results of kinetic investigations of the processes of homo- and co-polymerization of ethylene in connection with the structure and characteristics of magnesium supported titanium- and vanadium-catalysts and data on the microstructure and MMD of the polymers formed are reviewed. It is established that a number of effects such as increase in the reaction rate and molecular mass of the polymer formed in presence of an α-olefin, rise in the copolymerization constant of ethylene with α-olefins with rise in the temperature of synthesis and aspects of the microstructure of the copolymers are inexplicable within the known concepts. It is shown that the factor determining the special nature of the process of copolymerization of ethylene with α-olefins on titanium- and vanadium- magnesium catalysts is the specific solvation of the propagation centres by the molecules of the α-olefin or the modifying additive.