Premium
Isothermal crystallization behavior of metallocene‐catalyzed isotactic polypropylene
Author(s) -
Park Deukkil,
Kim Il,
Han YangKyu,
Seul SooDeuk,
Kim BuUng,
Ha ChangSik
Publication year - 2004
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.21253
Subject(s) - tacticity , materials science , spherulite (polymer physics) , crystallization , polymer chemistry , metallocene , post metallocene catalyst , polypropylene , composite material , chemical engineering , polymerization , polymer , engineering
Isothermal crystallization behavior of isotactic polypropylene (iPP) synthesized using metallocene catalyst was investigated in this work. The isotacticity of the polypropylene was characterized by 13 C‐NMR spectroscopy. It was found that the melting temperature ( T m ) of the iPP is 123.51°C and the crystallization temperature ( T c ) is 93°C. The iPP synthesized in this work did not show a general increase of T m with an increase of crystallization temperature T c , due to the short crystallization time of 20 min and low molecular weight (number average molecular weight = 6,300). The iPP showed a tendency of increasing heat of fusion (Δ H f ) with decreasing crystallization temperature. All the spherulites of iPP samples showed negative birefringence. For the iPP sample crystallized at the highest T c (= 123°C, just below T m ), the spherulite showed a pronounced Maltese Cross and a continuous sheaf‐like texture aligning radially, which suggests that R ‐lamellaes are dominant in this spherulite. The crystalline structure of the iPP was also investigated by X‐ray diffraction. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 231–237, 2005