title: Rapid evaluation of catalysts and MAO activators by kinetics: what controls polymer molecular weight and activity in metallocene/MAO catalysts?
abstract: The influence of methylaluminoxane (MAO) catalyst activators of different concentrations and preparative histories on the performance of 1-hexene polymerisations was investigated by kinetic methods, using rac-Me2Si(2-Me-Benz[e]Ind)2ZrCl2 as the standard catalyst precursor. Fast sampling and analysis allow the time dependence of monomer conversion and the growth of the number-average polymer molecular weight to be determined at a sufficiently short timescale to make this a feasible method for routine catalyst evaluation. Differences in productivity, polymer molecular weight and active species count are shown to be primarily a linear function of the trimethylaluminium concentration. The results in toluene and heptane as solvents are compared; the data show that the inferior performance in heptane is due to a substantially lower active species concentration.
authors: Wolfson Materials and Catalysis Centre, School of Chemistry, University of East Anglia, Norwich, UK.
authors: Fabio
authors: F
authors: Ghiotto
authors: Chrysoula
authors: C
authors: Pateraki
authors: John R
authors: JR
authors: Severn
authors: Nic
authors: N
authors: Friederichs
authors: Manfred
authors: M
authors: Bochmann
mesh_terms: D000535:Aluminum / Q000737:chemistry*; D002384:Catalysis; D007700:Kinetics; D015394:Molecular Structure; D008970:Molecular Weight; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; D011108:Polymers; D000535:Aluminum