Exxonmobil Chemical Patents Inc.

Lisa B Stefaniak

Periagaram Srinivasan Ravishankar

Rainer Kolb

Phillip Thomas Matsunaga

Quintin Paul Ward Costin

Provided are processes for making polymer compositions, especially those with reduced or no gel formation in lubricating oils as identified by rheological and visual gel tests and which are useful as viscosity modifiers. The processes described herein aim to achieve this objective by adjusting the concentrations of the hydrogen feed(s) in the first and/or second polymerization reaction zones, preferably such that (a) the hydrogen feed concentration in the first polymerization reaction zone is 0.0-1.0 wt %, based on total weight of feed(s) of hydrogen, ethylene monomer, &#x3b1;-olefin comonomer, and solvent into the first polymerization reaction zone, and/or (b) the hydrogen feed concentration in the second polymerization reaction zone is 0.0-0.5 wt %, based on total weight of feed(s) of hydrogen, ethylene monomer, &#x3b1;-olefin comonomer, and solvent into the second polymerization reaction zone.

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Houston, TX, United States of America

Lisa B Stefaniak