Copolymerization of ethylene with 1-hexene and 1-octene: correlation between type of catalyst and comonomer incorporated

✍ Scribed by Raul Quijada; Jairton Dupont; Márcia S. Lacerda Miranda; Rosângela B. Scipioni; Griselda B. Galland

• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: English
• Weight: 425 KB
• Volume: 196
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.1995.021961210

✦ Synopsis

Abstract

The behaviour of catalytic systems based on zirconium compounds for the copolymerization of ethylene with 1‐hexene and 1‐octene is reported. The metallocenes (CH~3~)~2~SiCp~2~ZrCl~2~, Cp~2~ZrCl~2~ (Cp = η^5^‐cyclopentadienyl), C~2~H~4~[Ind]~2~ZrCl~2~ and (Ind = η^5^‐indenyl) were chosen for this study. The bridged catalysts, (CH~3~)~2~SiCp~2~ZrCl~2~ and C~2~H~4~[Ind]~2~ZrCl~2~, and the metallocene Cp~2~ZrCl~2~ showed similar catalytic activities for home‐ and copolymerization of ethylene with 1‐hexene. ^13^C NMR analysis showed that the composition of copolymerization products depends on the catalytic system, in other words, on the ligand structure of the transition metal. Copolymers obtained using the bridged catalysts have greater incorporation of comonomer. Thermal analysis and viscosity measurements demonstrated that an increase of the comonomer concentration reduces the melting point, the crystallinity and the molecular weight of the copolymer. Results from infrared spectroscopy showed that β‐elimination is one of the possible termination reactions. The monomer reactivity ratios r were determined for all catalytic systems using Fineman‐Ross and ^13^C NMR methods. The values of r~1~ (M~1~ = ethylene) and r~2~ (M~2~ = α‐olefin) showed an effect of the type of metallocene and of α‐olefin on the structure of the copolymer obtained.