Transient mechanics in dense hydrogel suspensions

The flow behavior of dense hydrogel suspensions displays a myriad of remarkable features, whose origin is poorly understood. In this work we focus on the effect of transient particle mechanics on the bulk flow behavior of the packings. We probe packing mechanics via standard rheology and custom intruder tests, both in transient and steady state driving, and via stress and strain control. We observe strong history dependence of the packing, various rate dependent features and a sensitivity to boundary conditions. We interpret our results in the context of the observed relaxation dynamics in particle-level contact mechanics.