METHODS OF REGULATING POLYMER PROPERTIES Russian patent published in 2018 - IPC C08F2/34 C08F4/24 C08F210/16 

FIELD: technological processes.

SUBSTANCE: invention relates to a method for controlling polymer properties in polymerization processes in which a chromium based catalyst is used. Method for the preparation of a polyolefin is described, comprising contacting a reaction mixture with a reduced chromium oxide catalyst in a gas phase reactor to produce a polyolefin. Reaction mixture contains a monomer and a comonomer. Reaction temperature in the gas-phase reactor is changed by 1 °C or more, whereby the gas mole ratio between the comonomer and the monomer changes by about 2 % or more and the level of comonomer content in the polyolefin at substantially constant density changes by about 2 % or more.

EFFECT: obtaining a good balance between the impact strength and the stress cracking resistance parameter under environmental conditions.

10 cl, 9 dwg, 2 tbl, 17 ex