Viscoelastic properties of concentrated suspensions

Abstract

The deformation observed during oscillatory shear of concentrated suspensions indicates the alternate occurrence of two structures: the first at small deformations gives rise to approximately linear viscoelastic behavior, while the second is a virtually undeformable structure formed at large deformations. The behavior at small deformation is characterized by a dynamic viscosity which at low frequencies is inversely proportional to the frequency: at higher frequencies the viscosity levels off. This transition is ascribed to sheet formation by the suspended particles during shear in the low frequency region; in the high frequency region sheet formation is less developed. In accordance with this interpretation is the deformation at which the undeformable structure originates, as a function of frequency. The origin of this structure is attributed to the following: once the shear leads to an increase in solid content in a part of the system, the apparent viscosity there rises which causes an additional increase in solid content. This finally leads to a blocking of further deformation.

Viscoelastic properties of suspensions with weakly interacting particles

“…[1][2][3][4] Characterization of the rheological behavior of concentrated suspensions may also be complicated by slip at the walls of the rheometer. 5,6 Viscoelastic properties of suspensions with high filler content were investigated by Bigg,7,8 Schreuder and colleagues, 9 Poslinski and colleagues, 10 Strivens, 11 Doraiswamy and colleagues, 12 and Kalyon and colleagues. 13 In other studies of viscoelastic properties of suspensions by Lakdawala and Salovey, 14 Matsumoto and colleagues, 15 Rong and Chaffey, 16 and Lobe and White, 17 the particle sizes were considerably smaller than the one in this study.…”

Time‐dependent rheological behavior of low‐density polyethylene white color masterbatches under dynamic stress field

“…An extensive review on thixotropy was written by Mewis 9. In suspension systems, time‐dependent behavior was often related to the breakdown or buildup of structures in the dispersions 10–17. Schreuder et al11 studied suspensions of untreated glass particles in dioctylphthalate (DOP), in which time‐dependent behavior was found.…”

“…In suspension systems, time‐dependent behavior was often related to the breakdown or buildup of structures in the dispersions 10–17. Schreuder et al11 studied suspensions of untreated glass particles in dioctylphthalate (DOP), in which time‐dependent behavior was found. They considered that during deformation, the solid particles arrangned themselves into a closed‐packed structure in a part of the system and thus the apparent viscosity increased, which led to an additional accumulation of solid particles and blocked further deformation.…”