2010/04/09 by Ajay Singh Negi, Negi, Ajay Singh, Chinedum O. Osuji +1
Agricultural and Biological Sciences · Materials Science · #Biocrusts and Microbial Ecology #FOS: Physical sciences #Material Dynamics and Properties #Polysaccharides Composition and Applications #Soft Condensed Matter (cond-mat.soft)
paper · pdf · doi:10.48550/arxiv.1004.1512
openalex publication_date 2010/04/09 · openalex created_date 2022/10/06 · openalex updated_date 2026/07/28
Dilute Laponite suspensions in water at low salt concentration form repulsive\ncolloidal glasses which display physical aging. This phenomenon is still not\ncompletely understood and in particular, little is known about the connection\nbetween the flow history, as a determinant of the initial state of the system,\nand the subsequent aging dynamics. Using a stress controlled rheometer, we\nperform stress jump experiments to observe the elastic component of the flow\nstress that remains on cessation of flow or flow quenching. We investigate the\nconnection between the dynamics of these residual stresses and the rate of\nphysical aging upon quenching from different points on the steady state flow\ncurve. Quenching from high rates produces a fluid state, G">G', with small,\nfast relaxing residual stresses and rapid, sigmoidal aging of the complex\nmodulus. Conversely, quenching from lower shear rates produces increasingly\njammed states featuring slowly relaxing stresses and a slow increase of the\ncomplex modulus with system age. Flow cessation from a fixed shear rate with\nvarying quench durations shows that slower quenches produce smaller residual\nstresses at short times which relax at long times by smaller extents, by\ncomparison with faster quenches. These smaller stresses are correlated with a\nhigher modulus but slower physical aging of the system. The characteristic time\nfor the residual stress relaxation scales inversely with the quench rate. This\nimplies a frustrated approach to any ideal stress-free state that succinctly\nreflects the frustrated nature of these glassy systems.\n