The effects of particle size on reversible shear thickening of concentrated colloidal dispersions

2001 ◽  
Vol 114 (23) ◽  
pp. 10514-10527 ◽  
Author(s):  
Brent J. Maranzano ◽  
Norman J. Wagner
Keyword(s):  
Particle Size ◽  
Shear Thickening ◽  
Colloidal Dispersions

STRUCTURAL PARAMETERS OF AQUEOUS COLLOIDAL DISPERSIONS OF FULLERENE C60

2019 ◽  
pp. 31-37
Author(s):  
V.Yu. Fokina ◽  
E.А. Kizima ◽  
I.V. Miheev ◽  
A.I. Ivankov ◽  
V.M. Garamus
Keyword(s):  
Particle Size ◽  
Fractal Dimension ◽  
Particle Size Distribution ◽  
Structural Parameters ◽  
Colloidal Dispersions ◽  
Fullerene C60 ◽  
Solvent Exchange ◽  
X Ray ◽  
Dense Nucleus ◽  
Exchange Technique

Two types of fullerene C60 water dispersions were investigated by a small-angle X-ray and neutron scattering. As a result, structural parameters of fullerene aggregates were obtained. The water dispersions were obtained by the solvent-exchange technique and by huge dilution of initial C60/Nmethylpyrrolidone solution. The structure organization of water dispersions is considered in respect to their technique preparation. It was shown that fullerene aggregates were characterized by highly polydispersity in size for all dispersions. In the case of son/nC60 dispersion it was found that fullerenes formed aggregates with a dense nucleus (namely a surface fractal) with a radius of 58 ± 1 nm and a fractal dimension of 2.3. In turn, the nmp/nC60 system was characterized by the branched aggregates with fractal dimension 1.5 and bimodal particle size distribution.

Rheology of colloids

Surfactants ◽  
2019 ◽  
pp. 400-424
Author(s):  
Bob Aveyard
Keyword(s):  
Strain Rate ◽  
Shear Strain ◽  
Shear Thickening ◽  
Rheological Behaviour ◽  
Maxwell Model ◽  
Colloidal Dispersions ◽  
Shear Strain Rate ◽  
Plastic Behaviour ◽  
Shear Thickening Fluids ◽  
External Forces

Lyophobic colloidal dispersions, aggregated surfactant systems, and polymer solutions, as well as foams and emulsions, can all be deformed by weak external forces; rheology is the study of deformation and flow of materials. Various rheological quantities arising from the response of a material to shear are defined. For liquids the stress, τ‎, applied is related to the rate of deformation, that is, the shear strain rate, γ̇. For Newtonian fluids τ‎ and γ̇ are linearly related and τ‎ / γ̇ is the viscosity, η‎. Other nonlinear relationships correspond to shear thinning and shear thickening fluids and to plastic behaviour in which there is a yield stress. Viscoelastic systems exhibit both viscous and elastic properties; such behaviour is often treated using the simple Maxwell model. Some illustrative experimentally observed rheological behaviour is presented.

Influence of Components on the Rheological Property of Shear Thickening Polishing Slurry

2016 ◽  
Vol 1136 ◽  
pp. 461-465
Author(s):  
Bing Hai Lyu ◽  
Wei Tao Dai ◽  
Hai Zhou Weng ◽  
Min Li ◽  
Qian Fa Deng ◽  
...  
Keyword(s):  
Particle Size ◽  
Shear Rate ◽  
Rheological Property ◽  
Base Fluid ◽  
Abrasive Particle ◽  
Weight Ratio ◽  
Shear Thickening ◽  
Key Factors ◽  
Shear Thickening Fluid ◽  
High Efficient

Shear thickening polishing (STP) method was newly developed to achieve high efficient and high quality finishing of complex curved surface. The shear thickening fluid based slurry is one of the key factors in STP process. Viscosity of different shear thickening polishing slurry (STPS) was tested by rheometer in this study. The influences of dispersed particle size and concentration, abrasive material, abrasive particle size and concentration on the rheological property of STPS were analyzed. The results show that smaller dispersed particle (5.5 or 13μm in this study) and relative higher concentration (50-55 wt.%) are better for shear thickening effect of the base fluid. The viscosity of base fluid increases from 0.15-0.3 Pa·s to 0.8-1.1 Pa·s under high shear rate. The participation of Al2O3 and diamond abrasive changes the rheological property little, and the viscosity of STPS reaches the highest value 1.8 Pa·s at shear rate 300 s-1. But SiC abrasive obviously destroys the shear thickening effect. SPTS with different Al2O3 abrasive concentration in this study presents almost same viscosity curve. It is inferred that the number of the abrasive particle but not the weight ratio plays the role to effect the rheological property of STPS.

scholarly journals Optimized Birch Bark Extract-Loaded Colloidal Dispersion Using Hydrogenated Phospholipids as Stabilizer

Pharmaceutics ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 832 ◽  
Author(s):  
Francis Kamau Mwiiri ◽  
Rolf Daniels
Keyword(s):  
Particle Size ◽  
Interfacial Tension ◽  
Profile Analysis ◽  
Average Particle Size ◽  
Colloidal Dispersions ◽  
Wound Dressings ◽  
Bark Extract ◽  
Phospholipid Content ◽  
Birch Bark ◽  
Average Particle

This study investigated the formulation and processing of aqueous colloidal dispersions containing a birch bark dry extract (TE) as the active substance and hydrogenated phospholipids (Phospholipon 90H) as stabilizer, which can be used in the preparation of electrospun wound dressings. Colloidal dispersions manufactured using a two-stage homogenization process had a bimodal particle size distribution, which was most significantly (p < 0.0001) affected by the phospholipid content. The size of the single particles decreased from an average particle size of about 4 µm to a particle size of approximately 400 nm. Dynamic interfacial tension studies performed using a profile analysis tensiometer (PAT) showed that the phospholipids strongly declined the interfacial tension, whereas a further decrease was observed when phospholipids were combined with birch bark extract. Interfacial viscoelasticity properties analyzed using the oscillating drop technique resulted in an increase of both interfacial elasticity and viscosity values. These results indicated that the phospholipids are preferentially located at the lipophilic/water interface and a stable film is formed. Furthermore, the results point to a synergistic interaction between phospholipids and TE. Confocal Raman microscopy (CRM) suggested that the TE is predominantly located in the oil phase and the phospholipids at the interface.

Effects of Particle Size and Polydispersity on the Depletion and Structural Forces in Colloidal Dispersions

Langmuir ◽  
1996 ◽  
Vol 12 (21) ◽  
pp. 5004-5010 ◽  
Author(s):  
X. L. Chu ◽  
A. D. Nikolov ◽  
D. T. Wasan
Keyword(s):  
Particle Size ◽  
Colloidal Dispersions ◽  
Structural Forces
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