Non-Newtonian Fluid-Like Behavior of Poly(Ethylene Glycol) Diacrylate Hydrogels Under Transient Dynamic Shear

Hydrogels exhibit a fluid-like viscous response under high shear strain rates with significant rate- and microstructure-dependent rheological properties. In this study, the transient shear response of poly(ethylene glycol) diacrylate (PEGDA) hydrogels is characterized by application of the power-law fluid model to incompressible Navier–Stokes equation of start-up planar Couette flow. To impart the necessary boundary conditions for model calibration, a split-Hopkinson pressure bar based single-pulse dynamic simple shear experiment is developed, in which unsteady momentum diffusion between two shear plates is measured using two-dimensional digital image correlation (DIC). The measured shear profiles and their characteristic self-similarity under these boundary conditions are utilized to calculate power-law exponent and transient-state viscosity via finite difference simulations.