USE OF DIFFERENT ALKOXYSILANES AS EXTERNAL DONORS IN MGCL2-SUPPORTED ZIEGLER-NATTA CATALYSTS TO OBTAIN PROPENE 1-BUTENE COPOLYMERS WITH DIFFERENT MICROSTRUCTURE

The effects of different alkoxysilane donors (Ph(EtO)3Si, Me(EtO)3Si and Ph2(EtO)2Si) have been compared in propene/1-butene copolymerization with MgCl2-supported Ziegler-Natta catalysts. The copolymers obtained were fractionated and the fractions characterized by C-13 NMR analysis. The influence of the different alkoxysilanes on the yield, the fraction distribution and the composition, the reactivity ratios and the number-average sequence lengths of all the fractions were analyzed. The results obtained show that it is possible to vary the characteristics of propene/1-butene copolymers by varying the bulkiness of the hydrocarbon substituent and/or the number of the alkoxy groups of the silane donor. It was also possible to correlate the effect of the silane donor on the homopolymerization stereochemistry and on the characteristics of the copolymers.