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Evidences of Long‐ C hain Branching in Ziegler‐ N atta Polyethylene Homopolymers as Studied via SEC ‐ MALS and Rheology
Author(s) -
Yu Youlu,
Rohlfing David C.
Publication year - 2013
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.201300019
Subject(s) - branching (polymer chemistry) , size exclusion chromatography , rheology , polyethylene , polymer , polymer chemistry , molar mass distribution , materials science , multiangle light scattering , elution , chemistry , chemical engineering , light scattering , chromatography , organic chemistry , composite material , scattering , physics , optics , enzyme , engineering
Summary Comprehensive polymer architectural studies were carried out on a group of Ziegler‐Natta (Z‐N) polyethylene homopolymers via size‐exclusion chromatography coupled with multi‐angle light scattering (SEC‐MALS) and rheology. Although Z‐N resins are traditionally viewed as linear polymers, both SEC‐MALS and rheology results strongly indicate that there are topological variations, presumably long‐chain branching (LCB) or possibly hyper‐branches, in this group of supposedly linear Z‐N homopolymers. These Z‐N homopolymers exhibit very complex elution behavior that resulted in anomalous elution profiles in SEC. It appeared that some high molecular weight (MW) and long‐chain branched components followed a non‐size exclusion separation mechanism on SEC columns, co‐eluting with low MW and linear polyethylene components, causing a delayed elution. The possible origin of LCB in these Z‐N polymers is also discussed.