ポリαメチルスチレン溶液の流動誘起相分離とその粘弾性

概要

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Flow-induced phase separation behavior of poly (α-methylstyrenes) in a θ solvent, n-undecyl anisitate and the related viscoelastic properties were studied by rheological and light scattering measurements. The critical shear rate for flow-induced phase separation was consistently determined from integrated intensity of light scattering under the flow and its change after the cessation of flow, as well as from time dependency of dynamic modulus measured after the cessation of flow. It was observed that first normal stress difference and excess shear stress are proportional to shear rate at the shear rate region higher than the critical ones for phase separation. These results are qualitatively consistent with the theories of Onuki (Phys. Rev. A, 35, 5149 (1987)) and Doi and Ohta (J. Chem. Phys., 95, 1242 (1991)). The relative magnitude of excess stresses can be explained if we assume existence of domain structure elongated in the flow direction. At the higher shear rate end of measurement, it was observed that the stresses become not stable and show tendency to diverse. Together with direct observation results of the sample under the flow, it was speculated that the flow-induced gelation occurred at such high shear rates.
日本レオロジー学会の論文