Viscosity and transient electric birefringence study of clay colloidal aggregation

Abstract

We study a synthetic clay suspension of laponite at different particle and NaCl concentrations by measuring stationary shear viscosity and transient electrically induced birefringence (TEB). On one hand the viscosity data are consistent with the particles being spheres and the particles being associated with large amount bound water. On the other hand the viscosity data are also consistent with the particles being asymmetric, consistent with single laponite platelets associated with a very few monolayers of water. We analyze the TEB data by employing two different models of aggregate size (effective hydrodynamic radius) distribution: (1) bidisperse model and (2) log-normal distributed model. Both models fit, in the same manner, fairly well to the experimental TEB data and they indicate that the suspension consists of polydisperse particles. The models also appear to confirm that the aggregates increase in size vs increasing ionic strength. The smallest particles at low salt concentrations seem to be monomers and oligomers.

Anomalous Diffusion: A Basic Mechanism for the Evolution of Inhomogeneous Systems

“…The recent interest in the study of complex systems has led to an increased focus on anomalous diffusion [4-7, 36, 42, 45], which has been described in biological systems [42][43][44], protostellar birth [47], complex fluids [48][49][50][51][52][53], electronic transportation [54][55][56][57][58][59], porous media and infiltration [60][61][62], drug delivery [63][64][65][66], fractal structures and networks [67][68][69][70][71], and in water's anomalous behavior [72][73][74], phase transitions in synchronizing oscillators [39,40,[75][76][77], to name a few.…”

Interplay of anisotropy in shape and interactions in charged platelet suspensions

“…Charged platelet suspensions, such as swelling clays [1][2][3][4][5][6][7][8], disk-like mineral crystallites [9][10][11][12][13][14][15][16] or exfoliated nanosheets [17][18][19][20][21][22] abound in natural as well as industrial environments. Such minerals can be found in various particle sizes varying between 10 nm up to a few micrometers and the majority of them have a platelet-like shape with high aspect ratio, typically ranging between 20 and 1000.…”

Liquid Crystalline Behavior and Related Properties of Colloidal Systems of Inorganic Oxide Nanosheets

“…Temporal birefrin-gence is also induced by electric field as known as electro-birefringence. Electro-birefringence of clay colloids was discovered in early 1960s, and have continuously been studied by a few research groups [127,128,129,130,131,132,133,134,135]. …”