Inhomogeneous Elastic Yielding after Planar Extension under Confinement

Entangled melts can be demonstrated to terminate homogenous uniaxial extension before reaching the steady flow state, due to localized yielding. Additionally, such melts break up after stepwise extension in absence of any ongoing extension. This is coined elastic yielding by us since its first report. To further explore the nature of the elastic yielding, we conduct lubricated squeezing to achieve planar extension with confinement. It is shown¹ that elastic yielding still occurs in an inhomogeneous manner, “breaking up” without breakup. This result adds to the current understanding presented in Chapter 12 of the book “Nonlinear Polymer Rheology”.²

1. Yuan, R.; Wang, S.-Q. Inhomogeneous chain relaxation of entangled polymer melts from stepwise planar extension in absence of free surface. J. Rheol. 2020, 64, (5), 1251-1262 DOI 10.1122/8.0000093.
2. Wang, S.-Q., Nonlinear Polymer Rheology: Macroscopic phenomenology and Molecular foundation. Wiley: Hoboken, NJ, 2018.