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Flow behavior of symmetrical P (S‐ b ‐MMA) block copolymers: Rheological problems arising from shear modified morphology
Author(s) -
Braun H.,
Gleinser W.,
Cantow H.J.
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.1993.070490313
Subject(s) - rheology , viscoelasticity , rheometer , materials science , copolymer , small angle x ray scattering , morphology (biology) , shear flow , shear (geology) , scanning electron microscope , composite material , creep , shear rate , shear stress , polymer chemistry , thermodynamics , polymer , scattering , optics , physics , genetics , biology
In this article, symmetrical, narrow distribution P (S‐ b ‐MMA) block copolymers are characterized rheologically, using a dynamic spectrometer and a stress rheometer. The shear induced morphology changes are investigated by off‐line electron microscopy and SAXS. We tried to correlate the results of dynamics and long‐time creep experiments with morphological and rheological features. Summarizing, one can point out that the examined block copolymers reveal the well‐known low frequency behavior of phase separated blends. Additionally, we observed a significant shear influence on the morphology, i.e. a shear induced structuring and alignment of lamellae. This considerable change in morphology is also reflected by the characteristic rheological properties (retardation time, yield stress). Therefore, problems concerning the validity range of linear viscoelastic behavior arise, which are discussed in brief. © 1993 John Wiley & Sons, Inc.