Metallocene and Ziegler-Natta catalyzed polypropylene utilizing 1-heptene

[摘要] ENGLISH ABSTRACT: This study concerns the copolymerization of propylene with l-heptene. Thepercentage of l-heptene used as co-monomer in the polymerization reactions wasvaried from 5% to 20% in order to compare a variety of polymers with differentpercentages of comonomer incorporated. A variety of different catalysts were usedfor these polymerizations.Two metallocene catalysts were used: (A) the isospecific catalyst, rae-[ethylene bis(l-indenyl)]zirconium dichloride (rac-Et(Ind)2ZrCh2) and (B) thesilylene-bridged catalyst, rac-Me2Si(2-MeBenz[ e]Ind)zZrCh2. Methylaluminoxane(MAO) was used as cocatalyst for these two metallocene catalysts. Another series ofpolymerization reactions was done using a Ziegler-Natta catalyst, namelyTiCb/AlEt3/Si02.Characterization of the copolymers included usmg high temperature gelpermeation chromatography (HTGPC) for molecular mass and molecular massdistributions, differential scanning calorimetry (DSC) and dynamic mechanicalanalysis (DMA) to investigate the thermal and mechanical properties of thecopolymers, nuclear magnetic resonance spectroscopy (NMR) for informationconcerning the microstructures of the copolymers and crystallization analysisfractionation (CRYSTAF) to investigate the short chain branching of the copolymers.Comparative studies were done on the different catalysts and the polymerproperties. The synthesized polymers were also compared with copolymers ofpropylene with l-hexene and l-octene.

[发布机构] Stellenbosch University