Addition of Lewis bases and acids. Effect on α-olefins polymerization with soluble metallocenes, 2 Propylene

BELELLI, PATRICIA GABRIELA; FERREIRA, MARÍA LUJÁN; DAMIANI, DANIEL EDUARDO

MACROMOLECULAR CHEMISTRY AND PHYSICS

WILEY-V C H VERLAG GMBH

Año: 2000 vol. 201 p. 1466 - 1475

1022-1352

In this paper the soluble system rac-Etnd2ZrCl2/methylaluminoxane (MAO) was studied inpropylene polymerization with additives. Lewis acid andbase such as AlCl3 and ethyl benzoate (EB) were used toevaluate their effects on polymerization kinetics, catalystactivities and polymer properties. The results obtainedshow a trend to improve the performance when AlCl3 isadded. The activity is decreased with EB, but the effect itnot as strong as for ethylene (see Part 1). To further elucidatesome of the different aspects of metallocene activationand reactivation in the reaction media, several reactionswere carried out using different preactivation steps,with and without AlCl3. The preactivations were carriedout taking account of the different results obtained withboth additives (AlCl3 and EB). The pretreatment with EBwas not considered because the activity is decreased inthe polymerization. AlCl3 improves the activity when it ispresent during the preactivation step, but the presence ofEB in the reactor during the polymerization step has a poisoningeffect. These results show the importance of thepreactivation step carried out without olefin. The molecularweight of polypropylene obtained remains almostunchanged in all the evaluated conditions. A complete discussionof ethylene and propylene results is included, takingaccount of Part 1 and 2.