We describe an unexpected constitutive transition in entangled polymer solutions. At and beyond a critical stress, the initial spatially homogeneous and well-entangled sample transforms from its entangled (coiled) state into a fully disentangled (stretched) state over a period during which the resulting shear rate increases in a spatially inhomogeneous fashion. In the mode of controlled shear rate, the sample exhibits a stress plateau over three decades. Flow birefringence and normal stress observations unravel additional features of these flow phenomena.
Physical Review Letters
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Copyright 2003 American Institute of Physics. The original published version of this article may be found at http://dx.doi.org/10.1103/PhysRevLett.91.198301.
Tapadia, Prashant and Wang, Shi-Qing, "Yieldlike Constitutive Transition in Shear Flow of Entangled Polymeric Fluids" (2003). College of Polymer Science and Polymer Engineering. 108.