Steady-state extensional viscosity of a linear polymer solution using a differential pressure extensional rheometer on a chip

Abstract

In our earlier theoretical work [Lee and Muller, J. Rheol. 61, 1049–1059 (2017)], we proposed a design for a differential pressure extensional rheometer (DPER) on a chip. Here, we implement the DPER to evaluate the steady-state viscosity of a semidilute poly(ethylene oxide) solution at high and low extension rates. At low extension rates, the extensional viscosity exhibits strain thinning behavior with a power-law exponent of −0.5. At intermediate extension rates, the extensional viscosity exhibits strain thickening. At high extension rates, the extensional viscosity plateau has been estimated, and the corresponding finite extendable nonlinear elastic (FENE) constant is evaluated as 482. A novel method to determine the FENE constant and the extensional relaxation time distribution is presented, which are key parameters for the understanding of the extensional flow of a linear polymer solution.