TY - JOUR
T1 - Viscoelastic properties of low molecular weight symmetric poly(styrene-b-2-vinylpyridine)s in the ordered and disordered states under steady shear flow
AU - Takahashi, Yoshiaki
AU - Fang, Long
AU - Takano, Atsushi
AU - Torikai, Naoya
AU - Matsushita, Yushu
N1 - Copyright:
Copyright 2013 Elsevier B.V., All rights reserved.
PY - 2013
Y1 - 2013
N2 - Viscoelastic properties of symmetric poly(styrene-block-2-vinylpyridine)s in the ordered and disordered states under steady shear flow are examined for relatively low molecular weight samples at melt based on the temperature dependence of interaction parameter x. Since both components have almost the same viscoelastic properties, data for block copolymers and components are directly compared. In the disordered state near the ODT, two constant values for shear viscosity η, η°1 and η°2 at lower and higher shear rates, γ, respectively are obtained for diblock samples and η°1 coincided with the value obtained by dynamic flow measurements, which are higher than the values for components. The constant values of Je are obtained at γ range where η°2 are obtained, which are also higher than those of components. It was concluded that higher η°1 and lower η°2 values are due to the fluctuation effects and their suppression by the flow with higher γ, respectively. It was also concluded that fluctuation effects on viscoelastic properties completely disappear at around xN< 2 - 3 for SPs. In the ordered state, well aligned state was only attained for the sample having lowest molecular weight. The values of η° and Je obtained in well aligned state are consistent with those in disordered state, denoting that there is no discontinuity of data due to ODT.
AB - Viscoelastic properties of symmetric poly(styrene-block-2-vinylpyridine)s in the ordered and disordered states under steady shear flow are examined for relatively low molecular weight samples at melt based on the temperature dependence of interaction parameter x. Since both components have almost the same viscoelastic properties, data for block copolymers and components are directly compared. In the disordered state near the ODT, two constant values for shear viscosity η, η°1 and η°2 at lower and higher shear rates, γ, respectively are obtained for diblock samples and η°1 coincided with the value obtained by dynamic flow measurements, which are higher than the values for components. The constant values of Je are obtained at γ range where η°2 are obtained, which are also higher than those of components. It was concluded that higher η°1 and lower η°2 values are due to the fluctuation effects and their suppression by the flow with higher γ, respectively. It was also concluded that fluctuation effects on viscoelastic properties completely disappear at around xN< 2 - 3 for SPs. In the ordered state, well aligned state was only attained for the sample having lowest molecular weight. The values of η° and Je obtained in well aligned state are consistent with those in disordered state, denoting that there is no discontinuity of data due to ODT.
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U2 - 10.1678/rheology.41.83
DO - 10.1678/rheology.41.83
M3 - Article
AN - SCOPUS:84878382759
VL - 41
SP - 83
EP - 91
JO - Nihon Reoroji Gakkaishi
JF - Nihon Reoroji Gakkaishi
SN - 0387-1533
IS - 2
ER -