(116b) Effect of Non-Equilibrium Parameters on the Aging of Thermoreversible Colloidal Suspension

Colloidal gels are an important component of industrial and consumer products ranging from personal care, food and pharmaceuticals to cement, asphalt and mining tailings. Based on the ubiquitous nature of colloidal gels, it is of fundamental interest to understand the impact of various non-equilibrium parameters governing the macroscopic changes in the colloidal systems. In this work, we present new results for the characterization of aging in a well-studied model system of adhesive hard spheres (AHS) quenched below the spinodal. The system is comprised of a moderately concentrated suspension of octadecyl coated silica in n-tetradecane undergoing thermoreversible gelation. Recently, the system has been reported to show an anomalous rheological behavior in the form of a reproducible drop in shear modulus during aging at a deep thermal quenched state, which has been attributed to arrested phase separation (Suman and Wagner, The Journal of Chemical Physics 157 (2), 024901 2022). We study the kinetics of transition from homogeneous gel to heterogeneous gel upon deep thermal quench over a wide range of temperature ramp rates used to achieve the target quenched state. Furthermore, we investigate the effect of mechanical and thermal rejuvenation on aging behavior of AHS dispersion. Our rheological characterization at different amplitudes, temperature ramp rates and pre-shear history shows intriguing effects of non-equilibrium parameters on the kinetics of aging behavior shows intriguing effects of non-equilibrium parameters on the kinetics of aging behavior of colloidal gels. This study of phenomenon of aging in model colloidal gel system is of both fundamental importance and industrial relevance in determining the shelf-life of products based on colloidal gels.