Aging observed in soft glassy materials inherently affects the rheological properties of these systems and has been described by the soft glassy rheology (SGR) model [S. M. Fielding et al., J. Rheol. 44, 323 (2000)]. In this paper, we report the measured linear rheological behavior of thermosensitive microgel suspensions and compare it quantitatively with the predictions of the SGR model. The dynamic moduli [G[prime](omega,t) and G[double-prime](omega,t)] obtained from oscillatory measurements are in good agreement with the model. The model also predicts quantitatively the creep compliance J(t−tw,tw), obtained from step stress experiments, for the short time regime [(t−tw)<tw]. The relative effective temperature [script X]/[script X]g obtained from both the oscillatory and the step stress experiments is indeed less than 1 ([script X]/[script X]g<1) in agreement with the definition of aging. Moreover, the elasticity of the compressed particles (Gp) increases with increased compression, i.e., the degree of hindrance and consequently also the bulk elasticity (G[prime] and 1/J) increases with the degree of compression.
|Number of pages||8|
|Journal||Physical review E: Statistical, nonlinear, and soft matter physics|
|Publication status||Published - 2007|