Intrinsic viscosity of SiO2, Al2O3 and TiO2 aqueous suspensions

Rubio-Hernández, F.J.; Ayúcar-Rubio, M. F.; Velázquez-Navarro, J. F.; Galindo-Rosales, Francisco J.

doi:10.1016/j.jcis.2006.01.009

Cited by 78 publications

(49 citation statements)

References 27 publications

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“…It is shown that the only variable that has a significant effect in the range of variables studied is the solid content, which has a positive effect, as can be seen in Figure 7. It is known that the viscosity of a suspension increases on adding solid particles due to the hydrodynamic interactions as well as the colloidal interactions that take place in the fluid flow [28][29][30][31]. It can be seen that on increasing the solid mass load from 0.02 to 0.10 there is no significant increase, but when raised from 0.10 to 0.20 the viscosity rises significantly due to the increase in the interactions and collisions among particles that lead to the formation of agglomerates.…”

Section: Viscosity ηmentioning

confidence: 99%

Characterization of silica–water nanofluids dispersed with an ultrasound probe: A study of their physical properties and stability

et al. 2012

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of silica-water nanofluids dispersed with an ultrasound probe: A study of their physical properties and stability. Powder Technology, 2012, Vol. 224 AbstractThe stability and agglomeration state of nanofluids are key parameters for their use in different applications. Silica nanofluids were prepared by dispersing the nanoparticles in distilled water using an ultrasonic probe, which has proved to be the most effective system and gives the best results when compared with previous works. Results were obtained concerning the influence of the solid content, pH and salt concentration on the zeta potential, electrical double layer, viscosity, elastic and viscous moduli, particle size and light backscattering. Measurement of all these properties provides information about the colloidal state of nanofluids. The most important variable is the solid content.Despite the agglomeration due to high concentration, nanofluids with low viscosity and behaving like liquid were prepared at 20% of mass load thanks to the good dispersion achieved with the ultrasonic treatment. The pH of the medium can be used to control the stability, since the nanofluids are more stable under basic conditions far from the isoelectric point (IEP) and settle at pH = 2. Therefore, stable nanofluids for at least 48 h, with high solid content, can be prepared at high pH value (pH > 7) due to the electrostatic repulsion between particles.

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Section: Viscosity ηmentioning

confidence: 99%

Characterization of silica–water nanofluids dispersed with an ultrasound probe: A study of their physical properties and stability

et al. 2012

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“…For a nanocolloidal dispersion, a power series of volume fraction, which takes into account particle-particle interactions for several orders, was used to predict the viscosity [6]:…”

Section: Viscosity Modelmentioning

confidence: 99%

“…In the application of nanocolloidal dispersions, the viscosity, which is related to the required pumping power and diffusion properties, plays an important role in delivery systems. The rheological behavior of nanoparticle-fluid mixtures have been investigated experimentally [4][5][6][7]. Newtonian behavior has been observed for very dilute suspensions [4,7] and a considerable amount of effort has been devoted to determining the relationship between the viscosity and volume fraction of suspensions.…”

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confidence: 99%

“…This discrepancy could be caused by aggregation of the nanoparticles and an underestimated effective volume fraction of clusters [10,11]. Rubio-Hernandez et al [6] also noted that the intrinsic viscosity will be affected by the shape of aggregates, which could be changed by the pH and shear rate of a colloidal system.…”

mentioning

confidence: 99%

“…The aggregation of nanoparticles can simply be characterized as ellipsoidal with a certain effective size and axial ratio. The size and shape of aggregates can be determined from dynamic scattering light measurements and intrinsic viscosity data, respectively [6]. Aggregation is a dynamic process and the structure changes continuously because of Brownian motion.…”

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confidence: 99%

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Viscosity and aggregation structure of nanocolloidal dispersions

Wang

Luo

et al. 2012

Chin. Sci. Bull.

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In this work, the effects of nanoparticle size, particle volume fraction and pH on the viscosity of silicon dioxide nanocolloidal dispersions are investigated. Both size and pH are found to significantly affect nanocolloid viscosity. Two models are used to study the effect of aggregate structure on the viscosity of the nanocolloidal dispersion. The fractal concept is introduced to describe the irregular and dynamic aggregate structure. The structure of aggregates, which is considered to play an important role in viscosity, is affected by both intermolecular and electrostatic forces. The particle interaction is primarily affected by particle distance and becomes stronger with decreasing particle size and increasing volume fraction. The aggregate structure is also affected by the pH of the solution. Studying the relationship between pH and zeta-potential shows that with the neutralization of charges on the particle surface and decreasing electrical repulsion force, the particle interaction becomes dominated by attractive forces and the aggregates form a more compact structure. In recent years, nanocolloidal dispersions, which are heterogeneous mixtures consisting of very small particles with sizes typically in the order of 1-1000 nm, have attracted much attention for applications related to cooling [1], nanolubricants [2], drug delivery and diagnosis [3]. In the application of nanocolloidal dispersions, the viscosity, which is related to the required pumping power and diffusion properties, plays an important role in delivery systems. The rheological behavior of nanoparticle-fluid mixtures have been investigated experimentally [4][5][6][7]. Newtonian behavior has been observed for very dilute suspensions [4,7] and a considerable amount of effort has been devoted to determining the relationship between the viscosity and volume fraction of suspensions. Yu et al.[8] observed shear-thinning behavior when the volume concentration was higher than 0.03. An interesting phenomenon is that most of the viscosities are under-predicted by the traditional Einstein viscosity model [9,10]. This discrepancy could be caused by aggregation of the nanoparticles and an underestimated effective volume fraction of clusters [10,11]. Rubio-Hernandez et al.[6] also noted that the intrinsic viscosity will be affected by the shape of aggregates, which could be changed by the pH and shear rate of a colloidal system. The formation of aggregates can greatly change the transfer of heat and stress in a system because of their porous structure and large effective volume fraction. Particularly for nanocolloidal dispersions, the distance between aggregates can be in the order of several nanometers. The aggregation of nanoparticles can simply be characterized as ellipsoidal with a certain effective size and axial ratio. The size and shape of aggregates can be determined from dynamic scattering light measurements and intrinsic viscosity data, respectively [6]. Aggregation is a dynamic process and the structure changes continuously because of Brownian m...

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