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Characterization of fractionated LLDPE by DSC, FTIR, and SEC
Author(s) -
Neves Claudio J.,
Monteiro Elisabeth,
Habert Alberto C.
Publication year - 1993
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.1993.070500508
Subject(s) - comonomer , crystallinity , linear low density polyethylene , fourier transform infrared spectroscopy , fractionation , molar mass distribution , materials science , supercooling , polymer chemistry , polymer , analytical chemistry (journal) , fraction (chemistry) , chemistry , copolymer , chromatography , chemical engineering , thermodynamics , composite material , physics , engineering
Samples of ethylene / 1‐butene copolymer were fractionated according to chemical composition by preparative temperature rising elution fractionation (TREF) in the range of 27–117°C. The resulting fractions were submitted to DSC, SEC, and FTIR analyses. For each fraction, the methyl group content, melting temperature, crystallinity, average molecular weight, and molecular weight distribution were determined. From the results, it was found that the melting tempreature increased linearly with the extraction temperature in the range of low temperatures and remained constant at high temperatures. Similar behavior was observed for crystallinity. It was also verified that the first two fractions showed a higher degree of supercooling than the fractions extracted at higher temperatures. These results were explained by the existence of a heterogeneous intermolecular distribution of comonomer molecules. In a general way, the comonomer units, present at higher concentrations in the low temperature fractions, tended to destroy the crystalline order of the polymer. © 1993 John Wiley & Sons, Inc.