Scaling Behavior of the Rheological Properties of Montmorillonite Suspensions: Correlation between Interparticle Interaction and Degree of Flocculation

Ramos-Tejada, María del Mar; Arroyo, Francisco J.; Perea, R.; Durán, J.D.G.

doi:10.1006/jcis.2000.7370

Cited by 66 publications

(37 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[19][20][21][22] Moreover, it has been found that suspensions of sodium montmorillonite and similar clays exhibit a negative (anomalous) birefringence, 14,23,24 sparking interest in the phenomenon. The mentioned anomaly consists in the tendency of the particles to orient under some conditions with their major axis perpendicular to the external field, instead of parallel, as in "normal" EB.…”

Section: Introductionmentioning

confidence: 99%

Electric birefringence spectroscopy of montmorillonite particles

et al. 2016

View full text Add to dashboard Cite

Electric birefringence (EB) of suspensions of anisotropic particles can be considered an electrokinetic phenomenon in a wide sense, as both liquid motions and polarization of the electrical double layer (EDL) of the particles participate in the process of particle orientation under the applied field. The EB spectrum can be exploited for obtaining information on the dimensions, average value and anisotropy of the surface conductivity of the particles, and concentration and Maxwell-Wagner polarization of the EDLs. It is thus a highly informative technique, applicable to non-spherical particles. In this paper, we investigate the birefringent response of plate-like montmorillonite particles as a function of the frequency and amplitude of the applied AC electric field, for different compositions (pH, ionic strength, particle concentration) of the suspensions. The transient electric birefringence (i.e., the decay of the refractive index anisotropy with time when the field is switched off) is used for estimating the average dimensions of the particle axes, by modeling it as an oblate spheroid. The obtained values are very similar to those deduced from electron microscopy determinations. The frequency spectra show a very distinct behaviour at low (on the order of a few Hz) and high (up to several MHz) frequencies: the α and Maxwell-Wagner-O'Konski relaxations, characteristic of EDLs, are detected at frequencies above 10 kHz, and they can be well explained using electrokinetic models for the polarization of EDLs. At low frequencies, in contrast, the birefringence changes to negative, an anomalous response meaning that the particles tend to orient with their symmetry axis parallel to the field. This anomaly is weaker at basic pHs, high ionic strengths and low concentrations. The results can be explained by considering the polydispersity of real samples: the fastest particles redistribute around the slowest ones, inducing a hydrodynamic torque opposite to that of the field, in close similarity with results previously described for mixtures of anisometric particles with small amounts of spherical nanoparticles.

show abstract

Section: Introductionmentioning

confidence: 99%

Electric birefringence spectroscopy of montmorillonite particles

et al. 2016

View full text Add to dashboard Cite

show abstract

mentioning

confidence: 99%

“…Recently, we have reported the sol-gel transition behavior in laponite-MMT mixed clay dispersions 6 . On the other hand, visco-elastic properties of many clay suspensions have been extensively probed [7][8][9][10] through face (−)/edge (+) (FE) attraction form "house of cards" structures in acidic medium and band-like structures are formed through cation-mediated face (−)/face (−) (FF) attraction in alkaline medium 13 . The nature and mechanical strength of these microstructures formed are shown to be influenced by the structure and nature of the adsorbed additives 14 .…”

mentioning

confidence: 99%

Spontaneous evolution of self-assembled phases from anisotropic colloidal dispersions

2015

View full text Add to dashboard Cite

We investigate the spontaneous evolution of various self-assembled phase states from a homogeneous aqueous dispersion of high-aspect ratio Montmorillonite (Na Cloisite) nanoclay platelets grounded on the observations made over a period of 3.5 years. We have established the t w -c phase diagram for this system for the first time in salt-free suspensions under normal pH conditions using rheology experiments and have detected that these suspensions do undergo nontrivial phase evolution and aging dynamics. Distinctive phase separation, equilibrium fluid and equilibrium gels in the t w -c phase space are discovered. Cole-Cole plots derived from rheology measurements suggested the presence of inter connected network-like structures for c > c g, c g being the gelation concentration. All dispersions formed stable sols during the initial time, and with aging networklike structures were found to form via two routes: one for c < c g , by phase separation and another for c > c g , through equilibrium gelation. This has invoked and called for a revisit of the phase diagram of aging MMT dispersions.Emergence of anisotropic interaction between patchy colloids give rise to an array of unusual and novel soft materials like empty liquids with vanishing density, arrested networks and equilibrium gels which do not necessarily follow an underlying phase separation process to be borne. Recent research in patchy colloids has thrown up possibilities for intelligent design and development of structured nano-assemblies following a bottomup approach. These systems are inherently rich in dynamics, and a hierarchy of time and length scales adequately defines the properties of the soft matter so formed. Phase stability of dispersions of anisotropic particles has been of much scientific debate in the recent times. Many phase diagrams have been conceived and proposed for colloidal particles having different degree of geometrical anisotropy, namely rods, platelets, disks etc in their dispersion states [1][2][3] . Clays are discotic platelets with varying aspect ratio and surface charge density, and their dispersions exhibit an array of soft matter phases that evolve with waiting time t w as well as solid concentration c. Thus, the t w -c phase diagram is replete with non-trivial and equilibrium soft matter phases continuously evolving with time. From the application point of view, suspensions of clays offer unique properties, including their ability to form arrested states like gels, glasses and liquid crystalline structures under ambient conditions. Remarkably, compared to spherical colloids, clay platelets exhibit gel and glass phases at very low concentrations, which owe their origin to their unique geometrical structure and surface charge heterogeneity.In this work we demonstrate the spontaneous evolution of various self-assembled phases from a homogeneous aqueous dispersion of Montmorillonite (MMT, platelet diameter 250 nm and thickness 1 nm) nanoclay platelets based on the observations made over a period of 3.5 years. We have established ...

show abstract

“…Three types of experiment were performed: 17 Viscometry, or steady-state measurements. A shear stress ramp was applied to the suspensions under study.…”

Section: Rheological Measurementsmentioning

confidence: 99%

“…At rest, cohesive forces produce the characteristics of a solid, but when the fluidity limit is exceeded the bonds break and the product behaves as a fluid. 17,18 The yield stress was higher at the natural pH of the latex, indicating a higher degree of internal structure, but it was notably affected by temperature (Figs. 2 and 3).…”

Section: Viscometrymentioning

confidence: 99%

Rheological properties of ethylcellulose latex

Gallardo

Morales

López-Viota

et al. 2006

J of Applied Polymer Sci

View full text Add to dashboard Cite

Because of their large specific surface area, aqueous-based pseudolatex systems of ethylcellulose can absorb large amounts of drugs. In addition, the stability of polymeric particles in biological fluids delays the release of the drug as in controlled drug delivery systems. The aim of the present study was to characterize the rheological properties of latex particles as a measure of their colloidal stability. Here, we report the effect of three variables: pH, electrolyte concentration, and temperature. The rheograms clearly show that the polymer suspensions displayed Bingham plastic behavior. Internal structuring of the latex was greatest at acid and natural pH values, particularly at the highest ionic strength. In acid solutions, only temperature appeared to play a fundamental role; both the shear stress corresponding to the onset of nonlinear viscoelasticity and the elastic modulus at all frequencies were higher at 378C than those at room temperature. This is assumed to be a consequence of deformation of the polymer particles upon heating. The effect of ionic strength was noticeable only at the natural pH (pH % 6.5). At high concentrations of sodium chloride, the particles aggregated because of the decrease in double layer repulsion, and as a result, the latex became structured and its elastic modulus subsequently increased. Interestingly, when the temperature was increased further, this structure presumably broke, down, at least partially, and the storage modulus was reduced.

show abstract

Scaling Behavior of the Rheological Properties of Montmorillonite Suspensions: Correlation between Interparticle Interaction and Degree of Flocculation

Cited by 66 publications

References 28 publications

Electric birefringence spectroscopy of montmorillonite particles

Electric birefringence spectroscopy of montmorillonite particles

Spontaneous evolution of self-assembled phases from anisotropic colloidal dispersions

Rheological properties of ethylcellulose latex

Contact Info

Product

Resources

About