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Simultaneous Deconvolution of the Bivariate Distribution of Molecular Weight and Chemical Composition of Polyolefins Made with Ziegler‐Natta Catalysts
Author(s) -
Alghyamah Abdulaziz A.,
Soares João B. P.
Publication year - 2009
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.200800592
Subject(s) - natta , deconvolution , molar mass distribution , bivariate analysis , catalysis , chemical composition , ziegler–natta catalyst , composition (language) , polymer science , materials science , polymer chemistry , chemistry , mathematics , organic chemistry , polymer , statistics , composite material , polymerization , philosophy , linguistics , ethylene
Polyolefins made with Ziegler–Natta catalysts have non‐uniform distributions of molecular weight (MWD) and chemical composition (CCD). The MWD is usually measured by high‐temperature gel permeation chromatography (GPC) and the CCD by either temperature rising elution fractionation (TREF) or crystallization analysis fractionation (CRYSTAF). A mathematical model is needed to quantify the information provided by these analytical techniques and to relate it to the presence of multiple site types on Ziegler–Natta catalysts. We developed a robust computer algorithm to deconvolute the MWD and CCD of polyolefins simultaneously using Flory's most probable distribution and the cumulative CCD component of Stockmayer's distribution, which includes the soluble fraction commonly present in linear low‐density polyethylene (LLDPE) resins and have applied this procedure for the first time to several industrial LLDPE resins. The deconvolution results are reproducible and consistent with theoretical expectations.