Synthesis of polypropylene-co-p-methylstyrene copolymers by metallocene and Ziegler–Natta catalysts

✍ Scribed by H. L. Lu; S. Hong; T. C. Chung

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 149 KB
• Volume: 37
• Category: Article
• ISSN: 0887-624X
• DOI: 10.1002/(sici)1099-0518(19990801)37:15<2795::aid-pola14>3.0.co;2-l

✦ Synopsis

This paper discusses the copolymerization reaction of propylene and pmethylstyrene (p-MS) via four of the best-known isospecific catalysts, including two homogeneous metallocene catalysts, namely, {SiMe 2 [2-Me-4-Ph(Ind)] 2 }ZrCl 2 and Et(Ind) 2 ZrCl 2 , and two heterogeneous Ziegler-Natta catalysts, namely, MgCl 2 /TiCl 4 / electron donor (ED)/AlEt 3 and TiCl 3 . AA/Et 2 AlCl. By comparing the experimental results, metallocene catalysts show no advantage over Ziegler-Natta catalysts. The combination of steric jamming during the consective insertion of 2,1-inserted p-MS and 1,2-inserted propylene (k 21 reaction) and the lack of p-MS homopolymerization (k 22 reaction) in the metallocene coordination mechanism drastically reduces catalyst activity and polymer molecular weight. On the other hand, the Ziegler-Natta heterogeneous catalyst proceeding with 1,2-specific insertion manner for both monomers shows no retardation because of the p-MS comonomer. Specifically, the supported MgCl 2 / TiCl 4 /ED/AlEt 3 catalyst, which contains an internal ED, produces copolymers with high molecular weight, high melting point, and no p-MS homopolymer.