Negative thixotropy in ferric-oxide suspensions

Kanai, Hiroyuki; Amari, Takeshi

doi:10.1007/bf00396021

Cited by 19 publications

(11 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Shear thickening though, is not generally observed in colloidal systems with sufficiently strong attractive interactions to form flocculated gels and is presumed not to occur [7]. It has been reported in a handful of systems to date [8,9,10], although the complex composition of the suspensions studied in some cases makes it difficult to unambiguously study the mechanism.We have studied the steady state flow behavior of dilute, simple hydrocarbon dispersions of carbon black particles and, surprisingly, observe shear thickening above a composition dependent critical flow rate,γ c ≈ 10 2 − 10 3 s −1 . The shear modulus of gels formed by pre-shearing above the critical shear thickening rate displays an interesting power law dependence on the stress applied during the pre-shear.…”

mentioning

confidence: 99%

Highly anisotropic vorticity aligned structures in a shear thickening attractive colloidal system

Osuji

Weitz

2008

Soft Matter

View full text Add to dashboard Cite

Vorticity aligned cylindrical flocs of carbon black particles are formed in steady flow at low shear rates, and strikingly, appear as transient structures in the flow response of gels produced by the quenching of high rate shear thickening flows.Structure formation in response to flow is common in soft materials and complex fluids and is dependent on the nature of the cohesive forces in the system, time scales for diffusive motions and hydrodynamic interactions. For Brownian systems with hard sphere or repulsive interactions, distortion of the microstructure due to an imposed shear rate occurs when the timescale for flow is smaller than that for diffusion. The relative strength of flow forces compared to thermal or diffusive forces can be gauged by the dimensionless Péclet numberFor P e 1 the system displays isotropic arrangements of particles, but for P e > 1 the timescale associated with flow dominates that for diffusive relaxation. Under these conditions, the system becomes anisotropic due to separation of particles along the elongational axis and aggregation along the compressional axis [1]. String formation by alignment along the flow direction is typical in dilute systems at high shear rates and further structuring may take place by periodic arrangement of these strings in the vorticity-gradient plane. In more concentrated suspensions, hydrodynamic interactions lead to the formation of hydro-clusters and a shear thickening or jamming transition [2,3]. In systems with constitutive instabilities due to a negative slope in the stress-strain curve, co-existence between different deformation states under a single applied stress gives rise to shear banding along the velocity gradient direction [4]. For attractive systems, structure formation as discussed above is also found. Additionally, the alignment of particles or constituents along the vorticity axis has been reported and has emerged as a somewhat general phenomenon [5,6]. Shear thickening though, is not generally observed in colloidal systems with sufficiently strong attractive interactions to form flocculated gels and is presumed not to occur [7]. It has been reported in a handful of systems to date [8,9,10], although the complex composition of the suspensions studied in some cases makes it difficult to unambiguously study the mechanism.We have studied the steady state flow behavior of dilute, simple hydrocarbon dispersions of carbon black particles and, surprisingly, observe shear thickening above a composition dependent critical flow rate,γ c ≈ 10 2 − 10 3 s −1 . The shear modulus of gels formed by pre-shearing above the critical shear thickening rate displays an interesting power law dependence on the stress applied during the pre-shear. This is well accounted for by the dependence of the cluster size on the applied shear stress, and the resulting increase in cluster number density [11]. Subsequent deformation of these shear thickened gels at low shear rates produces highly oriented vorticity aligned flocs that gradually break down into small isotropic ...

show abstract

mentioning

confidence: 99%

Highly anisotropic vorticity aligned structures in a shear thickening attractive colloidal system

Osuji

Weitz

2008

Soft Matter

View full text Add to dashboard Cite

show abstract

“…This negative thixotropic behavior occurs when the viscosity increases with time at a fixed shear rate. [58][59][60] This behavior can be found in suspensions with additives that promote electrosteric stabilization, 58,61 which was the case of the used additives in the present investigation.…”

Section: Rheological Behaviormentioning

confidence: 68%

Processing and strengthening of 58S bioactive glass‐infiltrated titania scaffolds

Mesquita‐Guimarães

Leite

Souza

et al. 2016

J Biomedical Materials Res

View full text Add to dashboard Cite

In this work, TiO ceramic scaffolds were fabricated by the replica method using polyurethane (PU) sponges. Suspensions with high solid content were used to achieve scaffolds with improved mechanical behavior. TiO ceramic suspensions were optimized by rheological studies using different additives. It was found that the composition with 0.5 wt % Darvan enhanced the covering of the sponge struts. PU sponges of 45 to 80 ppi (pore per inch) were well coated without clogging pores. A thermal treatment with varying holding times, temperatures and heating rates was adjusted. The influence of different pore sizes on mechanical strength was evaluated. It was possible to obtain TiO scaffolds with 90% porosity and high pore interconnectivity, having compressive strength exceeding 0.6 MPa. TiO scaffolds were filled up with a 58S bioactive glass suspension to impart bioactive character to the scaffolds. These hybrid structures presented mechanical strengthening of about 26-213% depending on their sponge porosity. The prediction for cells viability via zeta potential measures indicated that this hybrid material is very promising for scaffold application with -19 to -25 mV between pH of 7.35-7.45. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 590-600, 2017.

show abstract

“…With both negative thixotropy and rheopexy, the viscosity increases over time. A typical example of the negative thixotropy is found in a paper for ferric oxide reported by Kanai et al [15]. There are many reports dealing with "negative thixotropy".…”

Section: Introductionmentioning

confidence: 88%

Rheopectic Behavior for Aqueous Solutions of Megamolecular Polysaccharide Sacran

Amat Yusof,

Yamaki,

Kawai

et al. 2020

Biomolecules

View full text Add to dashboard Cite

The rheopectic behavior of sacran aqueous solutions, a natural giant molecular polysaccharide with a molecular weight of 1.6 × 107 g/mol, was investigated. When a low shear was applied to 1.0 wt.% sacran solution, the shear viscosity increased from 7.2 to 34 Pa·s. The increment in the viscosity was enhanced as the shear rate decreased. The shear viscosity was independent of the time at a shear rate of 0.8 s−1; simultaneously, thixotropic behavior was observed at shear rates higher than 1.0 s−1. A crossover was observed at 0.15 wt.% for the concentration dependence of both the viscosity increase and zeta potential, which was the vicinity of the helix transition concentration or gelation concentration. It was clear that the molecular mechanism for the rheopexy was different at lower and higher regions of the crossover concentration.

show abstract

Negative thixotropy in ferric-oxide suspensions

Cited by 19 publications

References 6 publications

Highly anisotropic vorticity aligned structures in a shear thickening attractive colloidal system

Highly anisotropic vorticity aligned structures in a shear thickening attractive colloidal system

Processing and strengthening of 58S bioactive glass‐infiltrated titania scaffolds

Rheopectic Behavior for Aqueous Solutions of Megamolecular Polysaccharide Sacran

Contact Info

Product

Resources

About