THE INFLUENCE OF CYCLOPENTADIENYL RING SUBSTITUENT STERIC AND ELECTRONIC EFFECTS ON THE ETHYLENE-ALPHA-OLEFIN COPOLYMERIZATION BEHAVIOR OF (CPR)(2)ZRCL2 ETHYLALUMOXANE CATALYSTS/

A series of (eta(5)-C(5)H(4)R)(2)ZrCl2 (R = H, Me, Et, Pr-i, (t)Bu, Si Me(3), Me(2)Ph,) complexes have been used in combination with ethylalu moxane to copolymerise ethene with cr-olefins (C-5-C-14) under constan t conditions (P = 9-12 bar; T = 50-80 degrees C). Activity decreased s ubstantially for olefin > C-8. Variations of the 1-hexene concentratio n ((CpEt)(2)ZrCl2 as catalyst) revealed rate enhancement at a 1-hexene /ethylene ratio of 1.0. Copolymer incorporation was low (<6%) as detec ted by melting points and C-13 NMR spectroscopy. A statistically desig ned approach (2(3) factorial) was used to investigate the influence of P,T and [1-hexene] on copolymer formation with (CpR)(2)ZrCl2 (R = H,( t)Bu). Complex interaction between the variables was detected but the results (R = (BU)-B-t) were dominated by [1-hexene].