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Synthesis of polyolefins with unique properties by using metallocene‐type catalysts
Author(s) -
Imanishi Yukio,
Naga Naofumi,
Tsubooka Michiyo
Publication year - 2003
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200390144
Subject(s) - polyethylene , copolymer , polymer chemistry , crystallinity , materials science , cyclopentane , crystal structure , ethylene , metallocene , post metallocene catalyst , melting point , catalysis , polymer , crystallography , organic chemistry , chemistry , polymerization , composite material
Copolymerization of ethylene and 1,5‐hexadiene (HD) by zirconocene catalysts proceeded via cyclization‐addition mechanism to form 1,3‐didsubstituted cyclopentane structure in the polyethylene chain. The 1,3‐cyclopentane structure was found to be taken in the crystalline structure of polyethylene (isomorphism) by partially chainging the trans zigzag chain into gauche conformation, thereby, inducing a transformation of orthorhombic crystal to pseudohexagonal crystal. Copolymerization of ethylene and cyclopentene (CPE) by zirconocene catalysts yielded copolymers having 1,2‐disubstituted cyclopentane structure in the polyethylene chain. The 1,2‐cyclopentane structure was not taken into the crystalline structure of polyethylene. The melting point ( T m ) and the crystallinity ( X c ) of polyethylene decreased by copolymerization of HD or CPE, and the T m ‐ and X c ‐decreasing effect of CPE was stronger than HD. For copolymers of propylene and HD or CPE obtained with isospecific zirconocene catalyst, the isomorphism was not ovserved.