An investigation of the effect of chain length on stereo-regulation with C2 symmetric metallocene catalysts

dc.contributor.advisorVan Reenen, A. J.
dc.contributor.authorAmer, Ismael
dc.contributor.otherUniversity of Stellenbosch. Faculty of Science. Dept. of Chemistry and Polymer Science.
dc.descriptionThesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2006.
dc.description.abstractThis study concerns the polymerization of propylene both in the presence and absence of molecular hydrogen. The percentage of hydrogen used as a terminating agent in the polymerization reactions was varied from 0.1 wt% to 15.0 wt% in order to compare a variety of polymers with different percentages of hydrogen incorporated. Two ansa metallocene catalysts were used: (A) rac-[ethylene bis(indenyl)] zirconium dichloride (rac-Et(Ind)2ZrCl2) and (B) dimethylsilyl-bis(2-methyl benzoindenyl) zirconium dichloride (rac-Me2Si(2-MeBenz[e]Ind)2ZrCl2). Methylaluminoxane (MAO) was used as cocatalyst for both of the two catalysts. Characterization of the polymers included using nuclear magnetic resonance spectroscopy (NMR) for information concerning the microstructure of the polymers, high temperature gel permeation chromatography (HT-GPC) for molecular weight and molecular weight distributions and differential scanning calorimetry (DSC) to investigate the melting point and crystallization behaviour of the polymers. The polypropylenes prepared with the dimethylsilyl-bis(2-methyl benzoindenyl) zirconium dichloride catalyst system were compared to the polypropylenes synthesized with ethylene-bis(indenyl) zirconium dichloride. In particular, the effects of hydrogen on the microstructure, molecular weight, molecular weight distribution, melting point and crystallization behaviour were investigated.en
dc.format.extent12624231 bytesen_ZA
dc.publisherStellenbosch : University of Stellenbosch
dc.subjectDissertations -- Polymer scienceen
dc.subjectTheses -- Polymer scienceen
dc.subjectMetallocene catalystsen
dc.titleAn investigation of the effect of chain length on stereo-regulation with C2 symmetric metallocene catalystsen
dc.rights.holderUniversity of Stellenbosch

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