Effect of geometrical confinement on the flow of soft microgel particle pastes

摘要: In this paper, we determine the effect of confinement on shear flow concentrated soft microgel particle suspensions. Utilizing a flexure-based microgap rheometer (FMR), aqueous suspensions swollen P(NIPAM-co-AA) particles 4μ m diameter at different volume fractions larger than 64 vol% are subjected to shearing deformations between plates separated by gaps 5–120μ while monitoring stress response rates. Describing evolution from balance elastohydrodynamic lubrication and elastic forces following approach Cloitre Bonnecaze, it could be shown that already below critical level order 10 diameters an increase interparticle pressure leads rising given rate in yielded regime. This is strongest for close closest packing, with two orders magnitude resistance when approaching single-particle level, whereas decreases raising concentration. Furthermore, that, onset yielding suspensions, increasing effective modulus, but not yield strain.