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Molecular characterization and rheological properties of modified poly(ethylene terephthalate) obtained by reactive extrusion
Author(s) -
Nguyen Quoc Tuan,
Japon Sonia,
Luciani André,
Leterrier Yves,
Månson JanAnders E.
Publication year - 2001
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.10830
Subject(s) - materials science , reactive extrusion , branching (polymer chemistry) , rheology , extrusion , gel permeation chromatography , composite material , epoxy , shear thinning , polymer chemistry , ethylene , molar mass distribution , shear rate , viscosity , chemical engineering , polymer , organic chemistry , chemistry , catalysis , engineering
The use of a tetrafunctional epoxy‐based additive to modify the molecular structure of poly(ethylene terephthalate) (PET) was investigated with the aim of producing PET foams by an extrusion process. The molecular structure analysis and shear and elongation rheological characterization showed that branched PET is obtained for 0.2, 0.3 and 0.4 wt% of a tetrafunctional epoxy additive. Gel permeation chromatography (GPC) analysis led to the conclusion that a randomly branched structure is obtained, the structure being independent of the modifier concentration. The evolution of shear and extensional behavior as a function of molecular weight ( M w ), degree of branching, and molecular weight distribution (MWD) were studied, and it is shown that an increase in the degree of branching and M w and the broadening of the MWD induce an increase in Newtonian viscosity, relaxation time, flow activation energy and transient extensional viscosity, while the shear thinning onset and the Hencky strain at the fiber break decrease markedly.