Copolymerization kinetics obtained by stopped-flow polymerization

Ethylene--propylene copolymerization was carried out over MgCl sub 2 -supported TiCl sub 4 catalyst with two different reaction schemes; i.e., stopped-flow copolymerization (SFC) and continuously-purged copolymerization (CPC). The reactivity ratio for each monomer was evaluated by Fineman--Ross and Kelen--Tudos methods. It was found that the SFC resulted in smaller value of ethylene reactivity ratio(r sub E ) and larger value of propylene reactivity ratio(r sub P ) than the CPC. This seems to be attributed to the different extent of interaction between catalytic Ti sites and aluminium alkyls, i.e. active site formation and its over-reduction. Graphs. 13 ref.--AA