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Effects of polymer structure on the onset of processing defects in linear low density polyethylenes
Author(s) -
Karbashewski E.,
Rudin A.,
Kale L.,
Tchir W. J.,
Schreiber H. P.
Publication year - 1991
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760312205
Subject(s) - branching (polymer chemistry) , linear low density polyethylene , materials science , extrusion , polyethylene , polymer , differential scanning calorimetry , low density polyethylene , high density polyethylene , molar mass distribution , size exclusion chromatography , polymer chemistry , gel permeation chromatography , composite material , thermodynamics , organic chemistry , chemistry , physics , enzyme
Linear low density polyethylenes are manufactured by copolymerizing ethylene with 1‐alkenes, yielding a linear polyethylene backbone with short side chains. Due to the nature of the catalyst used in the polymerizaton, multimodal branching distributions are typically obtained. In this report, we have investigated the processability of four 1‐octene linear low density polyethylenes as a function of the short chain branching distribution. Analytical techniques such as 13 C nuclear resonance spectroscopy, size exclusion chromatography, differential scanning calorimetry, and temperature rising elution fractionation, in particular were used to elucidate the molecular structure. Processability measurements were made using various extrusion techniques and dynamic mechanical analyses.It was determined that in the absence of any variations in molecular weight, the polymers with the higher proportions of linear polyethylene showed inferior processability In terms of onset of surface imperfections at lower extrusion rates. Polymers with worse processability characteristics also exhibited higher zero shear viscosities.