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Structure development under transient shear flow in semidilute polystyrene solution
Author(s) -
Murase Hiroki,
Kume Takuji,
Hashimoto Takeji,
Ohta Yasuo,
Mizukami Tohru
Publication year - 1996
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.19961040117
Subject(s) - shear rate , shear flow , shear (geology) , materials science , light scattering , intensity (physics) , polystyrene , simple shear , scattering , optics , mechanics , rheology , composite material , physics , polymer
The shear‐induced concentration fluctuations or phase separation of a semidilute solution comprised of polystyrene (PS) as a solute and dioctylphthalate (DOP) as a solvent (PS/DOP) was investigated by using real‐time and in‐situ shear‐small‐angle light scattering and shear‐phase‐contrast optical microscopy. When a transient shear flow with a fixed shear rate γ greater than a critical value γ C was imposed on the solution, a unique anisotropic scattering pattern was observed some time after onset of shear. This pattern was found to be identical to the “butterfly pattern” previously reported for the same solutions under steady shear flow with γ C . When the shear flow was ceased before the scattered intensity reached a steady state, the scattered intensity rapidly increased toward a maximum intensity, and then decreased toward the intensity of the quiescent solution with time. From the phase‐contrast microscopy, this immediate increment of the scattered intensity after the shear cessation was found to arise from the increment in amplitude of the concentration fluctuations along flow direction. The characteristic length scale of the fluctuations was about 2.5 μm in this experiment, almost independent of the shear rate imposed on the solution.