gh Khodarahmi - National Petrochemical Company, Petrochemical Research and Technology Company, P.O.Box 1435884711, Tehran, Iran. Polymer Group, Islamic Azad University, kashan branch, Qotb Ravandi Blvd., Kashan, Iran.
Mazyar Khakpour - Polymer Group, Islamic Azad University, kashan branch, Qotb Ravandi Blvd., Kashan, Iran.
s.m Ghafelebashi - National Petrochemical Company, Petrochemical Research and Technology Company, P.O.Box 1435884711, Tehran, Iran.
m.m Khorasani - National Petrochemical Company, Petrochemical Research and Technology Company, P.O.Box 1435884711, Tehran, Iran.

Two series of slurry ethylene/1-hexene copolymerizations by a mg(OEt)2-supported Ziegler–Natta catalyst were compared to investigate the effect of hydrogen on the kinetic features of copolymerization especially on the comonomer effect phenomenon. Rate of the polymerization reactions were measured by the control of the mass flow of ethylene into the reactor. Results showed that hydrogen has an important effect on the kinetic aspects of the copolymerization. It was illustrated that comonomer could raise the rate of polymerization only when the hydrogen is present in the reaction

Ethylene Copolymerization, Comonomer Effect, Kinetic, Hydrogen