TY - JOUR
T1 - Synthesis of polypropylene-co-p-methylstyrene copolymers by metallocene and Ziegler-Natta catalysts
AU - Lu, H. L.
AU - Hong, S.
AU - Chung, Tze-chiang
PY - 1999/8/1
Y1 - 1999/8/1
N2 - This paper discusses the copolymerization reaction of propylene and p-methylstyrene (p-MS) via four of the best-known isospecific catalysts, including two homogeneous metallocene catalysts, namely, {SiMe2[2-Me-4-Ph(Ind)]2}ZrCl2 and Et(Ind)2ZrCl2, and two heterogeneous Ziegler-Natta catalysts, namely, MgCl2/TiCl4/ electron donor (ED)/AlEt3 and TiCl3. AA/Et2AlCl. 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 (k21 reaction) and the lack of p-MS homopolymerization (k22 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 MgCl2/TiCl4/ED/AlEt3 catalyst, which contains an internal ED, produces copolymers with high molecular weight, high melting point, and no p-MS homopolymer.
AB - This paper discusses the copolymerization reaction of propylene and p-methylstyrene (p-MS) via four of the best-known isospecific catalysts, including two homogeneous metallocene catalysts, namely, {SiMe2[2-Me-4-Ph(Ind)]2}ZrCl2 and Et(Ind)2ZrCl2, and two heterogeneous Ziegler-Natta catalysts, namely, MgCl2/TiCl4/ electron donor (ED)/AlEt3 and TiCl3. AA/Et2AlCl. 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 (k21 reaction) and the lack of p-MS homopolymerization (k22 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 MgCl2/TiCl4/ED/AlEt3 catalyst, which contains an internal ED, produces copolymers with high molecular weight, high melting point, and no p-MS homopolymer.
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U2 - 10.1002/(SICI)1099-0518(19990801)37:15<2795::AID-POLA14>3.0.CO;2-L
DO - 10.1002/(SICI)1099-0518(19990801)37:15<2795::AID-POLA14>3.0.CO;2-L
M3 - Article
AN - SCOPUS:0032668992
SN - 0887-624X
VL - 37
SP - 2795
EP - 2802
JO - Journal of Polymer Science, Part A: Polymer Chemistry
JF - Journal of Polymer Science, Part A: Polymer Chemistry
IS - 15
ER -